CS2363 EE Question+Bank

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Prepared By Suresh Kumar. M Assistant Professor

Department of Computer Science and Engineering

219-Sri Venkateswara College of Engineering

QUESTION BANK

CS2363 Computer networks UNIT I

PART A

1. Define and compare LAN, WAN.

LAN

1.Scope of LAN is restricted to a

small/ single building

2. LAN is owned by same

organization

3. Data rate of LAN 10-100mbps

WAN

1. scope of WAN spans over large

geographical area country/

Continent

2. a part of n/w asserts are owned or

not owned

3 .Data rate of WAN is Gigabyte.

2. What is circuit switching?

In a circuit-switched network, a dedicated communication path is established between

two stations through the nodes of the network. That path is a connected sequence of

physical links between nodes.

3. What is packet switching?

In a packet-switched network, it‘s not necessary to dedicate transmission capacity

along a path through the network. Rather, data are sent out in a sequence of small

chunks, called packets. Packet switching is mainly used in terminal-to-computer and

computer-to-computer communications.

4. Define Full Duplex and simplex transmission system.

With Full duplex transmission, two stations can simultaneously send and receive data

from each other. This mode is known as two-way simultaneous. The signals are

transmitted in only one direction. One is the sender and another is the receiver.

5. Draw the diagram of twisted pair cable?

6. Why sliding window flow control is considered to be more efficient than stop and

wait flow control.

In sliding window flow control, the transmission link is treated as a pipeline that may

be filled with frames in transit. But with stop-and-wait flow control only one frame

may be in the pipe at a time.

7. List the various frequencies of wireless transmission.

Terrestrial Microwave (2GHz to 40GHz), Broadcast Radio (30MHz to 1GHz),

Infrared (3 x 1011

to 2 x 1014

).

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8. Draw the diagram of coaxial cable?

9. Draw the diagram of optical fiber?

10. Differentiate between lost frame and damaged frame? What is the difference

between stop and wait and sliding window protocol?

Lost frame is the frame that fails to arrive at the other side. The damaged frame is a

recognizable frame does arrive, but some of the bits are in error. In stop and wait

protocol, we can send one frame at a time where as in sliding window protocol we can

send multiple frames at a time.

11. What do you mean by error control and Flow Control?

Error control refers to mechanism to detect and correct errors that occur in the

transmission of frames. Flow control is a technique for assuring that a transmitting

entity does not overwhelm a receiving entity with data.

12. Define piggybacking.

The technique of temporarily delaying outgoing acknowledgment so that they can be

hooked onto the next outgoing data frame is widely known as piggybacking.

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13. What is OSI? Define HDLC.

OSI is Open Systems Interconnection and is developed by the International

Organization for Standardization (ISO). HDLC stands for High Level Data Link Control.

It has three stations, two links, and three types of data transfer.

14. What are the key elements of a protocol?

Protocol is used for communications between entities in a system and must speak the same

language. Protocol is the set of rules governing the exchange of data between 2 entities. It

defines what is communicated, how it is communicated, when it is communicated

Key elements of Protocol:

Syntax – It refers to the structure or format of data meaning the order in which they are

presented.

Semantics – It refers to the meaning of each section of bit. How to do interpretation.

Timing – When data should be sent and how fast they can be sent.

15. List the uses of a network access layer.

Exchange of data between the computer and the network

Sending computer provides address of destination

May invoke levels of service

Dependent on type of network used (LAN, packet switched etc.)

16. What are the uses of transport layer?

Reliable data exchange

Independent of network being used

Independent of application

17. What is protocol data unit (PDU)?

At each layer, protocols are used to communicate and Control information is added to

user data at each layer. Transport layer may fragment user data. Each fragment has a

transport header added and header consists of Destination SAP, Sequence number and

Error detection code.

18. What are the uses of internet layer in TCP/IP?

Systems may be attached to different networks

Routing functions across multiple networks

Implemented in end systems and routers

19. What is a layered Network Architecture?

A layer is created when a different level of abstraction occurs at protocol.

Each layer should perform a well defined function.

Function of each layer should be chosen using internationality standardized

protocols. Boundaries between should be chosen to minimize information flow

across the interfaces.

A set of layers and protocol is called network architecture. A list of protocols

used by a system is called protocol stack.

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20. What is the need for layering?

It reduces the design complexity.

It decomposes the problem of building a network into more manageable

components.

It provides a modular design, if we want to add some new service, you may

only need to modify the functionality at one layer, reusing the functions

provided at all other layers

21.Compare OSI and Internet Protocol.

OSI TCP

It distinguishes between It does not distinguish between

service,Interface,protocol service, interface, protocol

Protocols are well hidden Protocols are not just hidden

Dejure. Standard Fit Model Defacto standard Fit protocol then

then protocol model

In transport layer only connection In Transport layer choice is for

Oriented services are available Connection oriented/connection less.

It contains 7 layers It contains 5 layers

22. How do layers of the internet model correlate to the layers of the OSI model?

OSI TCP/IP

Physical Layer Physical Layer

Data Link Layer Network Access Layer

Network Layer IP Layer

Transport Layer TCP Layer

Session Layer Application Layer

Presentation Layer

Application Layer

23. What is the use of data link layer in OSI?

Frame synchronization: Data is divided by data link layer as frames ,a

manageable unit.

Flow Control: Sending station does not overwhelm receiving station.

Error Control: Any error in bits must be detected and corrected using some

mechanism.

Addressing: Two stations in a multi point that involved in transmission must

be specified using physical address

Access Control: When two or more devices are connected to the same link,

Access control mechanism is needed to determine which device has control

over the link at any given time.

24. Why is flow control and error control duplicated in different layers?

Like the data link layer, the transport layer is responsible for flow and error control .

Flow control and error control at data link layer is node-to-node level. But at transport

layer, flow control and error control is performed end-end rather than across a single

link.

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25. List the key ingredients of technology that determines nature of a LAN. List the

common topologies available for LAN.

Topology, Transmission medium and Medium access control technique are the

technology that determines nature of a LAN. Star Topology, Ring Topology Bus

Topology and Tree Topology are the topologies available for LAN.

26. What are the functions of physical layer and presentation layer?

Encoding/ decoding of signals, preamble generation/removal (for synchronization)

and Bit transmission/ reception are the functions of physical layer. Translation,

Encryption / Decryption, Authentication and Compression are the functions of

presentation layer.

27. What is mean by data communication?

Data communication is the exchange of data (in the form of 1s and 0s) between two devices

via some form of transmission medium (such as a wire cable).

28. What are the three criteria necessary for an effective and

efficient network? The most important criteria are performance, reliability and security. Performance of the network depends on number of users, type of transmission medium, the capabilities of the connected h/w and the efficiency of the s/w. Reliability is measured by frequency of failure, the time it takes a link to recover from the failure and the network’s robustness in a catastrophe. Security issues include protecting data from unauthorized access and viruses.

29. What are the three fundamental characteristics determine the

effectiveness of the data communication system?

The effectiveness of the data communication system depends on three fundamental characteristics:

Delivery: The system must deliver data to the correct destination. Accuracy: The system must deliver data accurately.

Timeliness: The system must deliver data in a timely manner.

30. What are the advantages of distributed processing?

Advantages of distributed processing include security/encapsulation, distributed databases, faster problem solving, security through redundancy and collaborative processing.

31. Why are protocols needed?

In networks, communication occurs between the entities in different systems. Two entities cannot just send bit streams to each other and expect to be understood. For

communication, the entities must agree on a protocol. A protocol is a set

of rules that govern data communication.

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32. Why are standards needed?

Co-ordination across the nodes of a network is necessary for an efficient communication. If there are no standards, difficulties arise. A standard

provides a modelor basis for development to which everyone has agreed.

33. For n devices in a network, what is the number of cable links

required for a Mesh and ring toplogy?

Mesh topology – n (n-1)/2, Ring topology – n

34. What is the difference between a passive and an active hub?

An active hub contains a repeater that regenerates the received bit patterns

before sending them out. A passive hub provides a simple physical connection between theattached devices.

35. Distinguish between peer-to-peer relationship and a primary-

secondary relationship. Peer-to-peer relationship: All the devices share the link equally.

Primary-secondary relationship: One device controls traffic and the others must transmit through it.

36. Assume 6 devices are arranged in a mesh topology. How

many cables are needed? How many ports are needed for each

device?

Number of cables=n (n-1)/2=6(6- 1)/2=15

Number of ports per device=n-1=6-1=5

37. Group the OSI layers by function.

The seven layers of the OSI model belonging to three subgroups. Physical, data link and

network layers are the network support layers; they deal with the physical aspects of

moving data from one device to another. Session, presentation and application layers are

the user support layers; they allow interoperability among unrelated software systems.

The transport layer ensures end-to-end reliable data transmission.

38. What are header and trailers and how do they get added and removed? Each layer in the sending machine adds its own information to the

message it receives from the layer just above it and passes the whole package to the layer just below it. This information is added in the

form of headers or trailers. Headers are added to the message at the layers 6,5,4,3, and 2. A trailer is added at layer2. At the receiving machine, the headers or trailers attached to the data unit at the

corresponding sending layers are removed, and actions appropriate to that layer are taken.

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39. The transport layer creates a communication between the source and destination. What are the three events involved in a connection?

Creating a connection involves three steps: connection establishment, data

transfer and connection release.

40. What is the DC component?

Direct current is a zero-frequency signal with constant amplitude.

41. How does NRZ-L differ from NRZ-I?

In the NRZ-L sequence, positive and negative voltages have specific meanings: positive for 0 and negative for 1. in the NRZ-I sequence,

the voltages are meaningless. Instead, the receiver looks for changes from one level to another as its basis for recognition of 1s.

42. What are the functions of a DTE? What are the functions of a DCE?

Data terminal equipment is a device that is an information source or an information sink. It is connected to a network through a DCE. Amplitude Time

1 0 0 0 0 0 0 0 0 0 0 1 0 0

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Data circuit-terminating equipment is a device used as an interface between a DTE and a network.

43. What does the electrical specification of EIA-232 describe?

The electrical specification of EIA-232 defines that signals other than data

must be sent using OFF as less than -3 volts and ON as greater than +3 volts. The data must be transmitted using NRZ-L encoding.

44. Discuss the mode for propagating light along optical channels.

There are two modes for propagating light along optical channels,

multimode and single mode.

Multimode: Multiple beams from a light source move through the core in

different paths.

Single mode: Fiber with extremely small diameter that limits beams to a

few angles, resulting in an almost horizontal beam.

45. What is refraction?

The phenomenon related to the bending of light when it passes from one

medium to another.

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46 What is meant by Ethernet and MAC control?

Ethernet is a networking topology developed in 1970 which is governed by the IEEE

802.3 specification. MAC control field contains any protocol control information

needed for the functioning of the MAC protocol. For example, a priority level could

be indicated here.

47 What is CSMA/CD?

It is a protocol used to sense whether a medium is busy before transmission but it has

the ability to check whether a transmission has collided with another.

48 List the rules for CSMA/CD.

1. If the medium is idle, transmit; otherwise go to step 2.

2. If the medium is busy, continue to listen until the channel is idle, and then transmit

immediately.

3. If a collision detected during transmission, transmit a brief jamming signal to all

station to indicate collision has occurred and then cease transmission.

4. After transmitting a jamming signal, wait for some time, then transmit again.

49 What is preamble?

A 7-octet pattern of alternating 0s and 1s is used by the receiver to establish bit

synchronization is called as preamble.

50 When a transmitting station will insert a new token on the ring?

It will insert a new token when the station has completed transmission of its frame.

The leading edge of the transmitted frame has returned to the station.

51 What is Early Token Release (ETR)?

ETR allows a transmitting station to release a token as soon as it completes frame

transmission, whether or not the frame header has returned to the station.

52 What is Frame Status (FS)?

It contains the error detected (E), address recognized (A), and frame coped (F)

indicators. Each indicator is represented by a symbol, which is R for ―reset‖ or

―false‖ and S for ―set‖ or ―true‖.

53 Give the applications of wireless LANs.

LAN extension, cross building interconnect, nomadic access, and advantages hoc

networks.

54 What is a bridge? List the reason for using bridges in LAN.

Bridge is a hardware networking device used to connect two LANs. A bridge

operates at data link layer of the OSI layer.

Reliability, performance, security, and geography are the reason for using bridges in

LAN

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55 What is No-transition?

A station of this type is either stationary or moves only within the direct

communication range of the communicating stations of a single BSS

(basic service set)

56 What are the functions of a bridge?

The function of a bridge between two LANs A and B are:

Reads all frames transmitted on A and accepts those addressed to stations on B

Using medium access control protocol for B, retransmits the frames onto B

Does the same for B-to-A traffic.

57 What is spanning tree routing?

The spanning tree approach is a mechanism in which bridges automatically develop a

routing table and update that table in response to changing topology.

58 Compare FDDI with token ring 802.5.

FDDI 802.5

No priority and reservation bits It has priority scheme by using

reservation bits.

No need of converting a token to start of

data frame by inverting token bits because

of high data rate

It converts a token to data frame

changing token frame.

A station that transmits data frames

releases a new token as soon as it

completes data.

A station that data transmissions after

releasing back its own transmission,

release the token.

59 Ethernet stipulates a minimum size of a frame. Why is it necessary?

To detect collision. To identify valid frame from garbage, valid full format

should contain 64 bytes from destination address to checksum. So if the data portion is less

than 46 bytes, pad field is used to fill out the frame to minimize size.

60 Give the format of Ethernet address.

Preamble

64

Dest addr

48

Src addr

48

Type

16

Body CRC

32

61 What is meant by the contention period of Ethernet? How many lines are

required to connect n – systems in Direct Mesh topology?

When several stations on an Ethernet have data to send, there are contention periods during

which collisions happen and no data is successfully transmitted.

n(n-1)/2 lines are required.

62 What does IEEE 10 Base 5 standard signify?

10 represents data rate 10 Mbps.

5 refers to segment length 5* 100 m that can run without repeaters

Base represents Base band communication

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63 Define Repeater, Hub.

Repeaters and hubs are interconnecting devices.

Repeater: Repeaters extends the Ethernet segment and it repeats the signal. It does

not amplifies the signal.

Hub: A Hub has several point to point segments coming out. It is a multi way

repeater. It broadcasts any signal through all outgoing lines.

64 What is meant by Exponential back of algorithm?

After first collision, each station waits either 0 or 1 slot time before trying again. If 2

stations collide and each one picks same random number 0/1,. .After second collision,

each one picks either 0,1,2 or 3 slot at random and waits. If collision occurs again , then

next time the number of slots to wait is chosen at random from 0 to [23 – 1]. This

algorithm is called binary exponential ―back off algorithm‖.

65. Define a switch and a bridge. Switches are hardware or software device capable of creating temporary connections between

more devices which are not directly connected. It is a multi input/output port device. It transfers

data coming from one input port to one or more output ports. This function is called as

forwarding. Bridges are used to interconnect LANs. A bridge observes and forwards all frames

that it receives.

66.Define Spanning Tree Algorithm.

Bridge connects n/w and removes loop in the path using spanning tree algorithm It constructs

a spanning tree of edges between hosts that maintain connectivity of the graph with no loops.

It is a dynamic algorithm. The algorithm works as Frame Forwarding, Address Learning and

Loop Resolution.

67. What are different types of bridge? What are the limitations of bridges?

Simple Bridge connect 2 LAN

Multi port Bridge connect more than 2 LANs

Transparent Bridge it learns on its own about connected LANs.

limitations of bridges:Scalability and Hetrogenity

68. Mention the functions of Bridges.

1. A bridge should have enough buffer space to store the frames until it is transmitted.

2. It should be able to distinguish addresses of host on different LAN.

3. It can contain information about other bridges.

. 4. It should follow congestion control mechanisms to overcome congestion.

5. It works at layer 1 and layer 2 level.

69.Name any two network connecting devices? Can a bridge replace repeater for

interconnecting 2 segments of a n/w?

Repeater repeats the signal to the actual strength so that they can travel and works at

physical layer. Repeater operates on the physical layer level. Here collision

probability is more.

Bridge is an network connecting device. It does forwarding & filtering frames using

LAN destination address. Bridges are used to connect LAN or WAN and works at

data link layer level. Collision Probability is more.

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A bridge cannot replace repeater for interconnecting 2 segments of a network because

functions of them are entirely different.

70.What are the advantages of switches? Write the frame format for FDDI.

In switches, the sending information are directly transmitted to the concern receiver.

8 8 48 48 32 8 24

Start of

Control

Dest Src

Body

CRC

End of

Status

frame addr addr

frame

71. What is Token ring? What is the use of bit stuffing?

Token ring is a set of nodes are connected together in a ring. Data flow always in a particular

direction around the ring. Bit stuffing is bit oriented protocol. It is used to detect the error

during the transmission of the stream of bits.

PART-B

1. List and discuss the various techniques available in error detection. (ReferWilliam

stallings)

2. Explain about internet architecture (ReferWilliam stallings)

3. Explain about OSI network architecture (ReferWilliam stallings)

4. Explain Sliding window flow control and stop and wait flow control in detail.(Refer

Peterson)

5. Explain about Token Ring andfiber distributed data(FDDI) interface in detail.(Refer

Peterson)

6. Explain in detail about IEEE 802.11 with example

7. Describe about link layer Flow Control. .(Refer Peterson)

8. Explain about Physical links and Channel access on links. (ReferWilliam stallings)

9. Discuss about Framing. .(Refer Peterson)

10. Describe about the layering and protocols. .(Refer Peterson)

11.Discuss the various line encoding techniques used to send analog and digital data on

digital channels. .(Refer Peterson)

12. Explain the Mesh and star topologies of the networks in detail with diagram.(Refer my

notes)

13. write short notes on transmission media. .(Refer Peterson)

14. with an example ,illustrate how CRC will calculate with an example. .(Refer my notes)

15. compare and contrast the Go-Back-N ARQ Protocol with selective repeat ARQ.

ReferWilliam stallings)

16. Explain in detail the error detection and error corrections.(ReferWilliam stallings)

17.Write in detail about Bluetooth and Wi-Fi. .(Refer Peterson)

18.Explain about learning Bridges and the spanning tree algorithm in detail. .(Refer

Peterson)

19. Explain the following: Switches and Bridges.(Refer Peterson)

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UNIT – II

PART A

1. Differentiate Packet Switching and circuit Switching.

Issue Datagram subnet Circuit Switching

2. What is Virtual circuit Switching? In the virtual circuit approach, the relationship between all packets belonging to a

message or session is preserved single route is chosen between sender and receiver at the

beginning of the session. When the data are sent all packets of the transmission travel one

after another along that route Virtual circuit transmission is implemented in two formats -

PVC, SVC.

3. What is Switched virtual circuit?

Here virtual circuit is created wherever is needed and exist only for duration of the

specific exchange. It can be used with connection establishment and connection termination.

4. What are the different types of source routing approach?

Rotation, Stripping off and Using pointers are the different types of source routing approach.

5. Define Unicasting, Broadcasting and Multicasting.

Unicasting: Transmitting data from a single sender to a single receiver.

Broadcasting: Transmitting data from a single source to all the other nodes in the network

Multicasting: Transmitting data from a single source to a group of destination nodes.

6. Classify the following addresses

23.85.48.119 --------- Class A, 127.24.34.56 ------------- Class A

159.78.9.10 ------------ Class B, 195.20.10.11. ------------ Class C

220.36.123.47 ------------ Class D, 245.31.220.225------------ Class 3

7. What is IP address?

An Internet Address is made of four bytes (32 bits) that define a host‘s connection to a

network. There are currently 5 different field lengths patterns, each define a class of

addresses. These are designed to cover the needs of different types of organizations, class A,

B, C, D, E.

Class Netid Hostid

Circuit setup Not Required Required

Transmission path No Transmission path dedicated path

Delay Packet transmission delay Call setup delay

Addressing Each packet contains the full

source and destination address

Only data is sent

Bandwidth Dynamic Bandwidth Fixed Bandwidth

Routing Each packet is routed

independently

Entire data is sent through the

same path

Congestion control Difficult Easy if enough buffers can be

allocated in advance for each VC

set up

Complexity In the transport layer In the network layer

Suited for Connection-oriented and

connectionless service

Connection-oriented service

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8. How many network addresses and host addresses are supported by class A, class B

networks?

Class A: Number of networks = 127

Number of hosts = 224

-1

Class B : Number of networks = 214

-1

Number of hosts = 216

– 1 = 65,535

9. Differentiate Physical Address and Logical Address.

Physical Address Logical Address

1. It is implemented by data link layer. It is implemented by n/w layer.

2. It contains 48 bits. It contains 32 bits

3. It is a local addressing system. It is an universal address system.

4. Another name MAC address. Another name IP address.

5. It is flat in nature Hierarchical in nature

6. Does not give any clue for routing Its structure gives clue for routing

10. Define Router.

A router operates as the physical, data link and network layer of the OSI model ,

A router is termed as an intelligent device. Therefore, its capabilities are much

more than those of a repeater or a bridge.

11. What does a router do when it receives a packet with a destination address that it

does not have an entry for, in its routing table?

Default Router: If IP Software is not able to find the destination, from routing table then it

sends the datagram to default router. It is useful when a site has small set of local address

connected to it and connected to the rest of the Internet.

12. Define ARP.

Associates an IP address with physical address. It is used to find the physical address of the

node when its Internet address is known. Any time a host/router needs to find the physical

address of another host on its network, it formats an ARP query packet that includes the IP

address and broadcasts it. All hosts in the network process the ARP packet but only the

required station sends back physical address.

13. Define RARP

Allows a host to discover its internet address when it knows only its physical address ( a

diskless computer). The host wishing to retrieve its internet address broadcasts an RARP

query packet that contains its physical address to every host on its physical network. A

server on the network recognizes the RARP packet and returns the host‘s internet address.

14. What do you mean by ICMP?

ICMP is an error reporting mechanism. It does not specify the action to be taken for each

possible error. The source must relate the error to an individual application program and take

other actions to correct the problem.

15. List out functions of IP.

IP services unreliable, best-effort, connectionless packet system.

Unreliable – delivery is not guaranteed

Connectionless – each pocket is treated independent from others

Best-effort delivery – it makes an earnest attempt to deliver packets.

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It defines basic unit of data transfer through TCP/IP.

IP s/w performs routing function – finds a path from source to destination.

IP includes a set of rules that embody the idea of unreliable packet delivery

16. What is the use of TTL in IP header?

It lets how long that datagram is allowed to live in the network. The source sets that

time. Routers and hosts in the path of that datagram should decrement TTL and

removes it when TTL = 0 and send an error message to the source. TTL is written hops or

time in seconds.

17. What is internetworking and what are its principles?

Internet is an interconnected set of networks. From outside it looks like a simply layer

n/w. A collection of communication networks interconnected by routers is called

internetworking. The principle of inter networks are provide a link between networks and

routing for delivery of packets.

18. What are the important fields in a routing table?

Destination, Cost and Next Hop

19. What is Trace route option?

Record Route/ Trace Route: Here source creates an empty list of IP addresses and

each router on the path of the datagram adds its IP address to the list whereas a router get a

datagram that has record route option, it adds its addresses to the list. To add, it compares

pointer & length. If pointer > length, the list is full. So host forwards a datagram without

inserting its address to it. Record route is useful only if source & destination agrees.

0 8 16 24 31

Code (7) Length Pointer

First IP address

Second IP address

20. Write the difference between Distance vector routing and Link state routing.

Distance Vector Routing Link state routing

1. Basic idea is each node sends its

knowledge about the entire network to its

neighbours.

1. Basic idea is every node sends its

knowledge about its neighbours to the

entire network

2. It is dynamic routing 2. It is dynamic routing

3. RIP uses Distance vector routing 3. OSPF uses link state routing

21. List some of the unicast routing protocols. Routing Information Protocol (RIP) for IP Open Shortest Path First (OSPF)

22. To whom ICMP reports error message?

ICMP allows routers to send error messages to other router or hosts. ICMP is an error

reporting mechanism. It does not specify the action to be taken for each possible error. It is

informing the source that the error has occurred and the source has to take actions to rectify the

errors.

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23. Which class IP addresses are used for multicast and unicast?

Unicast : Class A, Class B , Class C Multicast: Class D

24. What is Permanent virtual circuit ?

In this technique the same virtual circuit provided between two users on a continuous basis.

The circuit is dedicated to a specific user. No one else can use it. Because it always in place,

it can be used without connection establishment and connection termination

25. What is the use of a router?

A router is useful for interconnecting two or more heterogeneous networks that differ in

their physical characteristics such as frame size, transmission rates, topologies, addressing

etc. A router has to determine the best possible transmission path among several available

paths.

26. What is meant by hop count? The pathway requiring the smallest number of relays, it is called

hop-count routing, in which every link is considered to be of equal length and given the value one.

27. What are data grams?

In datagram approach, each packet is treated independently from all others. Even when one packet represents just a place of a

multipacket transmission, the network treats it although it existed alone. Packets in this technology are referred to as datagram.

28. What are the functions of MAC?

MAC sub layer resolves the contention for the shared media. It contains synchronization, flag, flow and error control specifications necessary

to move information from one place to another, as well as the physical address of the next

station to receive and route a packet.

30. What is protocol data unit?

The data unit in the LLC level is called Protocol Data Unit (PDU). It

contains four fields.

Destination Service Point Address DSAP)

Source Service Access Point

Control field

Information field

31. What are headers and trailers and how do they get added and removed?

The control data added to the beginning of a data is called headers. The control data added to the end of a data is called trailers. At the sending

machine, when the message passes through the layers each layer adds the headers or trailers. At the receiving machine, each layer removes the data meant for it and passes the rest to the next layer.

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32. What are the responsibilities of network layer?

The network layer is responsible for the source-to-destination delivery of packet across multiple network links. The specific responsibilities of network layer include the following:

Logical addressing.

Routing.

33. How the packet cost referred in distance vector and link state routing?

In distance vector routing, cost refer to hop count while in case of link state routing, cost is a weighted value based on a variety of factors such as security levels, traffic or the state of the link.

PART B (Refer all in Peterson)

1. What do you mean by switching? Explain Virtual circuit switching techniques.

2. (i) Explain Packet switching technique in detail.

(ii) Explain in detail about source routing approach.

3. Explain about Address Resolution Protocol.

4. Explain in detail about Dynamic Host Configuration Protocol and Internet Control

Message Protocol.

5. Explain the differences between the adaptive and non adaptive routing

6. (i) Explain in detail about IP addressing.

(ii) Explain the Datagram delivery and Forwarding in Internet Protocol.

7. Explain the IP datagram format, fragmentation and reassembly.

8. Explain the Routing Information protocol/Distance vector routing in detail.

9. Explain about the OSPF and Interdomain routing (BGP)routing algorithms.

10. Describe about Queuing discipline

11. Discuss about Subnetting and CIDR.

12. Describe about Ipv6

13. Describe distance Vector Routing

14. compare The distance Vector and Link state routing Protocol

15. Discuss in detail about the OSPF routing Protocol

16. Define fragmentation and Explain Why the IPV4 and IPV6 Protocol need to fragment

some packets

17. . Discuss in detail the various aspects of IPv6

18. Write short Notes on (1.)internet Protocol (2).Routers

19. Explain in detail about Distance vector routing protocol with an example

20. Discuss the various Switching Techniques used in networks

21. For The Routing Table shown Below, what does the router do with packets addressed to

the following addresses?

Subnet Number Subnet Mask Next hop

(1) 128.96.180.192 128.96.170.0 255.255.254.0 Interface 0

(2) 128.96.167.151 128.96.168.0 255.255.254.0 Interface 1

(3) 128.96.169.192 128.96.166.0 255.255.255.0 R2

(4) 128.96.165.121 128.96.164.0 255.255.252.0 R3

Default R4

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UNIT – III

PART A

1. Give any two Transport layer service

1. Multiplexing:-

Transport layer performs multiplexing/ demultiplexing function. Multiple

applications employ same transport protocol, but use different port number. According

to lower layer n/w protocol, it does upward multiplexing or downward multiplexing.

(eg) X.25 can have 4095 VC. Multiple services can use that single VC using upward

multiplexing. (eg) X.25 can use only 3bit/7bit/15bit sequence number. So a high

speed network may need a larger sequence space. For that downward multiplexing /

splitting used to improve throughput.

2. Reliability : [ Error Control and Flow Control ]

2. How an application process running in one host is addressed by another process

through TCP?

It uses socket address (host, port).

Port represents a particular transport service in a host.

3. What are the various adaptive retransmission policy of TCP.

Simple average

Exponential / weighted average

Exponential RTT backoff

Jacobson‘s Algorithm

4. What is the wrap around time for TCP Sequence Number. What is the Wrap

around time for T3 link with 45 Mbps data rate?

Once a segment with sequence x survives in Internet, TCP cannot use the same sequence

no. How fast 32-bit sequence no space can be consumed? 32-bit sequence no is adequate

for today‘s network. Wrap Around Time for T3-45Mbps (232

x 8)

/45Mbps=763.55sec=12.73 min

5. What do you mean by congestion?

Any given node has a number of I/O ports attached to it. There are two buffers at each

port—one to accept arriving packets & another one to hold packets that are waiting to

depart. If packets arrive too fast node than to process them or faster than packets can be

cleared from the outgoing buffers, then there will be no empty buffer.

The first such strategy is to discard any incoming packet for which there is no

available buffer space. The alternative is for the node that is experiencing these

problems to exercise some sort of flow control over its neighbors so that the traffic flow

remains manageable.

6. Name the policies that can prevent congestion.

a. Additive Increase Multiplicative decrease

b. Slowstart mechanism

c. Fast retransmit and fast recovery

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7. What is TINYGRAM?

1byte data + 20 byte IP header + 20 byte TCP header=41 byte => known as ‗

TINYGRAM‘overhead is more . ( - for one byte data over head is 40 byte)

8. Give the datagram format of UDP.

Source port address:- It is the address of the application program that has created the

message.

Destination port address:- It is the address of the application program that will receive

the message.

Source port

Address

16 bits

Destination port

Address

16 bits

Total Length

16 bits

Checksum

16 bits

Total Length :- It defines the total length of the user datagram in bytes.

Checksum :- It is a 16 – bit field used in error correction.

9. What is function of transport layer?

The protocol in the transport layer takes care in the delivery of data from

one application program on one device to an application program on

another device. They act as a link between the upper layer protocols and

the services provided by the lower layer.

9. What are the duties of the transport layer?

The services provided by the transport layer

End-to- end delivery

Addressing Reliable

delivery Flow control Multiplexing

11. What is the difference between network layer delivery and the

transport layer delivery?

Network layer delivery: * The network layer is responsible for the the source-to-destination delivery of packet

* The transport layer is responsible for source-to-destination delivery

of the entire message. Transport layer delivery across multiple network links. The transport layer

is responsible for source-to-destination delivery of the entire message.

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12. What are the four aspects related to the reliable delivery of data?

The four aspects are, Error control, Sequence control, Loss control,

Duplication control.

13. What is meant by segment?

At the sending and receiving end of the transmission, TCP divides long transmissions into smaller data units and packages each into a frame called a segment.

14. What is meant by segmentation?

When the size of the data unit received from the upper layer is too long for the network layer datagram or data link layer frame to handle, the transport protocol divides it into smaller usable blocks. The dividing

process is called segmentation.

15. What are the types of multiplexing?

The types of multiplexing are,

Upward multiplexing

Downward multiplexing

10. What are the two possible transport services?

Two basic types of transport services are,

Connection service

Connectionless services

16. The transport layer creates the connection between source and destination. What are the three events involved in the connection?

For security, the transport layer may create a connection between the two end ports. A connection is a single logical path between the source

and destination that is associated with all packets in a message. Creating a connection involves three steps:

Connection establishment

Data transfer & Connection release.

17. What is meant by congestion?

Congestion in a network occurs if user sends data into the network at a rate greater than that allowed by network resources.

18. Why the congestion occurs in network?

Congestion occurs because the switches in a network have a limited

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buffer size to store arrived packets. 19. What is meant by quality of service?

The quality of service defines a set of attributes related to the performance of the connection. For each connection, the user can request a particular

attribute each service class is associated with a set of attributes.

20. What are the two categories of QoS attributes?

The two main categories are

User Oriented

Network Oriented

21. List out the user related attributes?

User related attributes are

SCR – Sustainable Cell Rate

PCR – Peak Cell Rate

MCR- Minimum Cell Rate

CVDT – Cell Variation Delay Tolerance

22. What are the networks related attributes?

The network related attributes are,

Cell loss ratio (CLR)

Cell transfer delay (CTD) Cell delay

variation (CDV) Cell error ratio (CER)

23. What are the rules of nonboundary-level masking?

The bytes in the IP address that corresponds to 255 in the

mask will be repeated in the subnetwork address.

The bytes in the IP address that corresponds to 0 in the

mask will change to 0 in the subnetwork address

For other bytes, use the bit-wise AND operator.

24. Define Gateway.

A device used to connect two separate networks that use different

communication protocols.

25. What is LSP?

In link state routing, a small packet containing routing information sent by a router to all other router by a packet called link state packet.

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26. What is the main difference between TCP & UDP?

TCP UDP

It provides Connection oriented service Provides connectionless service.

Connection Establishment delay will be

there

No connection establishment delay

Provides reliable service Provides unreliable, but fast service

It is used by FTP, SMTP It is used by audio, video and

multimedia applications.

27. Give some examples for situations using UDP.

It is very useful for audio or video delivery which does not need

acknowledgement. It is useful in the transmission of multimedia data.

28. How does TCP sender window size change using effective window?

Calculation of effective window: TCP on Receiver side must keep

Last Byte Received – Last Byte Read <= Max Rcv Buffer.

It advertises a window size of Advertised window = Max Rev buffer – (Last

ByteReceived – Last ByteRead )(i.e.) free space in received buffer.

TCP on sender side

Sender calculates an effective window,

Effective Window = Advertised window –(Last Byte sent – Last Byte Acknowledged)

If Effective. Window > 0 Source can send data.

29. What are the different phases in TCP state machine?

Connection Establishment, Data transfer and Connection Release

30. How check sum is calculated in TCP?

To compute checksum, UDP/TCP prepends a pseudo header to datagram.

Source IP address

Destination IP address

Zero Protocol TCP

Length

Pseudo header is not transmitted nor they included in length. To compare checksum,

Store zeroes in CHECKSUM field

Entire object (pseudo header, header , data) is divided into 16 bits.

Added & taken ones complemented.

31. What is SYN segment?

It is used to start a TCP connection and provides agreement between sender and

receiver on sequence number

32. Name the policies that can prevent congestion.

a. DEC bit.

b. Random Early Detection(RED).

c. Source based congestion avoidance.

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33. How do transport services differ from the data link layer services?

The data link layer services are at node to node level. But the transport layer services are

end to end level. Both the layers are having the flow control and error control mechanisms.

The data link layer offers at node to node level. But the transport layer offers at end to end

level. Data link layer is responsible for node to node delivery of the frames while transport

layer is responsible for end to end delivery of the entire message.

34. What are the TCP services to provide reliable communication?

Error control,Flow control,Connection control and Congestion control

35. Define the DEC bit mechanism.

Each router under this mechanism monitors the load and explicitly notifies the end nodes

when congestion is going to occur. This notification is implemented by setting a binary

congestion bit which is known as DEC bit, in the header of the packet that follows to the

router. The destination host copies this DEC bit into the corresponding ACK and sends back

to source. Now source can adjust its sending rate to avoid congestion.

36.List out various congestion control and congestion avoidance techniques

congestion control: AIMD, slow start, Fast retransmit and Recovery

congestion avoidance techniques: DEC bit , RED

37. What is a bus topology?

Bus topology uses a multipoint medium and all stations are attached through

appropriate hardware interfacing known as a tap. A full duplex operation is used for

transmission and reception of data in a bus.

38. What is tree topology?

Tree topology is generalization of bus topology. Transmission medium is a branching

cable with no closed loops. It begins at a point known as headend, where one or more

cables start, and each of these may have branches.

39. What is ring topology?

In the ring topology, the network consists of a set of repeaters joined by point-to-

point links in a closed loop. The repeater is a device which receives data in one link

and transmits them in other link.

40. What is star topology? List the advantages of it.

In star topology, each station is directly connected to a common central node. Central

node is referred as star coupler which uses two point-to-point links, one for transmission

in each direction. Its advantages are scalable and easy to identify the fault.

41. What is ARQ? What are the two types of error in flow control and error control?

Automatic Repeat Request is used to retransmit the information automatically when

the packet is lost while transmit. The two types of error in flow control and error control are

single bit error and burst error.

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42. What is peer to peer process?

Communication between peer to peer process, a protocol defines a communication

service that it exports locally, along with a set of rules governing the messages that

the protocol to implement this service.

PART B [Refer only in Peterson]

1. Write short notes on (i) TCP segment format.(ii) Wrap around time.

iii) silly window syndrome.

2. Explain TCP sliding window algorithm for flow control.

3. (i) Explain DECbit mechanism in detail. (8)

(ii)Explain the slow start mechanism. (8)

4. Describe about congestion control algorithms in detail

5. Discuss about congestion avoidance algorithm in detail.

6. Explain Adaptive retransmission policy in detail.

7. Explain the real transport protocol of UDP and how will you calculate checksum in

UDP? What is the significance of Pseudo Header in UDP?

8. Explain the TCP Connection establishment and termination using Timeline diagram.

9. Explain TCP state Transition diagram.

10. Explain the significance of Clark‘s solution and Nagle‘s algorithm

11. Explain connection establishment and connection closing in TCP.

12. What is PUSH mechanism? Explain CODE BITS in TCP header.

13. Explain the working of TCP using The state Diagram

14. Explain adaptive flow control in detail and its uses

15. How the connection is established using three-way handshaking, explain in detail

16. Discuss briefly about the techniques used to improve Qos

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UNIT – IV

PART A

1.lossless compression

Ensures that the data recovered from the compression/decompression process

is exactly the same as the original data. A lossless compression algorithm is used to

compress file data, such as executable code, text files, and numeric data, because programs

that process such file data cannot tolerate mistakes in the data.

2. lossy compression

does not promise that the data received is exactly the same as the data

sent. This is because a lossy algorithm removes information that it cannot later restore.

Hopefully, however, the lost information will not be missed by the receiver. Lossy algorithms

are used to compress still images, video, and audio.

3. Delta encoding,

simply encodes a symbol

as the difference from the previous one. Thus, for example, AAABBCDDDD would

be represented as A001011000. Note that delta encoding is likely to work well for

encoding images where adjacent pixels are similar. It is also possible to perform RLE

after delta encoding, since we might find long strings of 0s if there are many similar

symbols next to each other.

4. Block Diagram for JPEG Compression

5. DCT phase

In jpeg compression,The first phase applies the discrete cosine transform (DCT) to the block.

If the image is a signal in the spatial domain, then DCT transforms this signal

into an equivalent signal in the spatial frequency domain. This is a lossless operation

but a necessary precursor to the next, lossy step. It takes

an 8 × 8 matrix of pixel values as input and outputs an 8 × 8 matrix of frequency

coefficients.

6.Quantization phase:

It is the second phase of JPEG compression where the insignificant bits of the frequency

coefficients obtained from DCT phase are dropped. This phase is lossy.

7.Encoding phase:

This is the final phase of JPEG compression where the quantized frequency coefficients are

encoded in a compact form. This results in additional compression, but this compression is

lossless.

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8.Data compression:

The goal of data compression,

is to remove as much redundancy from the data as possible,

so that we may encode it in as few bits as possible. There is a requirement that the sending

and receiving hosts to process every byte of data in the

message

9. Authentication means verifying the identity of the remote Participant.

10.Digital signature:

A digital signature is a special case of a message integrity code, where the code can have

been generated only by one participant.eg. RSA signature, where, a given participant

is the only one that knows its own private key, the participant uses this key to produce

the signature

11.Public and Private key:

Any of several encryption algorithms (e.g., RSA), in which

each participant has a private key (shared with no one else) and a public key (available

to everyone). A secure message is sent to a user by encrypting the data with that user‘s

public key; possession of the private key is required to decrypt the message, and so

only the receiver can read it.

12. Cryptographic hash functions

typically don‘t involve the use of keys. Instead, the idea is to map a potentially large

message into a small fixed-length number, analogous to the way a regular hash function

maps values from a large space into values from a small space.

13.Define PKI.

Public Key Infrastructure(PKI), is a complete scheme for certifying binding between

public key and identities. PKI starts with ability to verify the identities and bind them to keys

OUT-of-Band.(range something ouside the n/w).

14. Define X.509 authentication.

One of the major standard for certicates is known as X.509.It includes

a) Identity of the entity being certified

b) Public key of the entity being certified

c) Identity of the signer

d) Digital signature

e) Dig Sig Algorithm identifier

f) Timer Expiration(optional)

15.Define CA.

Certification Authority(CA) is an entity claim to be trust worthy for verifying identities

and issuing public key certificates. They are classified as Commercial CA, Govermental

CA and Even Free CA. You must use own keys if CA is used. It is also known as Self

certifying certificates.

17.Define Nonce.

Nonce is the random number which is used only once in the message.

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18. Define PGP.

Pretty good Privacy(PGP) is the widely used approach to provide security for Email.

It provides authentication, confidentiality, data integrity and Non-repudiation.

19. Define Handshake protocol in security.

A pair of of TLS participants negotiate at run time which cryptography to use.

The participants negotiate the choice of

a) data integrity Hash, MD5 or SHA used to implement HMAC.

b) Symmetric key cipher for confidentiality among the possibilities are DES, AES ,

3DES

c) Session key establishment approach .

20. Define Record Protocol.

With in session establish by the handshake protocol TLS record protocols add

confidentialty and integrity to the underline transport services. Messages handed down from

the application layer are

a) Fragmented or coalesced into blocks of convenient size.

b) Optionally compressed

c) Integrity protected using Hmac.

d) Encrypted using a symmetric key cipher.

e) Past to the transport layer for transmission.

21.Define Firewalls.

A firewall is a system that is a sole point of connectivity between the sited it protects and

the rest of the network.

22. Define Demilitarized Zone(DMZ).

DMZ is used to hold services such as DNS and Email server that need to be accessible to

the outside.

22. Define Packet filter.

It filter the packet from third person using firewall mechanism, but it will not detect the

state of the packet where it arrive.

Part B.

1.Explain in detail about Video Compression.(Refer in Peterson)

2. Explain in detail about Image Compression.(Refer in Peterson)

3.Explain in detail about Audio Compression.(Refer in Peterson)

4.Explain in detail about PGP.(Refer in William stallings)

5. Explain in detail about TLS and IP security. .(Refer in Peterson)

6. Discuss in Detail about Firewalls. .(Refer in William stallings)

7.Disucuss in detail about Kerberos. .(Refer in Peterson)

8. Explain in detail about key predistribution. .(Refer in Peterson)

9.Explain in detail abot Diffie-Hellmann Algorithm.(Refer in Peterson)

10.Explain in detail about modes of operation in security.(Refer in William stallings)

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UNIT – V

PART A

1. List the capabilities provided by the SIP (Session Intimation Protocol).

User location

User availability

User capabilities

Session setup

Session management

2. What is the Domain Name System responsible for?

The Domain Name System converts domain names (of the form www.vtubooks.com)

into IP numbers.

3. Why do we need a Domain Name System? What role does the DNS Resolver play

in the DNS system?

IP numbers uniquely identify hosts on the Internet: however they are difficult to remember.

We therefore need a memorable way of identifying hosts. A DNS Resolver is responsible for

making requests of the local DNS server in behalf of clients.

4. How does a DNS Resolver bootstrap the Domain Name Lookup process?

A DNS Resolver must know the IP address of at least one DNS server. It uses this

address to start the DNS Lookup process.

5. What are the four main properties of HTTP?

Global Uniform Resource Identifier.

Request-response exchange.

Statelessness.

Resource metadata.

6. What are the four groups of HTTP Headers?

The four groups of HTTP headers are General headers, Entity Headers, Request

Headers and Response Headers.

7. What is WWW and SMTP?

The SMTP is used for connection between sending mail. WWW is an internet

application that allows user to view pages and move from one web page to another.

8. What do you mean by active web pages?

When a client send a HTTP request for an active Web page, the Web server sends back an

HTTP response that contains an HTML page as usual. HTML page also contains a small

program that executes on the client computer inside the Web browser.

9. What are the transmission modes of FTP?

i. Stream mode: Default mode and data is delivered from FTP to TCP as a continuous

stream of data.

ii. Block mode: Data is delivered from FTP to TCP in terms of blocks. Each data block

follows the three byte header.

http://www.vtubooks.com/

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iii. Compressed mode: File is compressed before transmitting if size is big. Run length

encoding method is used for compression.

10. Compare the HTTP and FTP:

S.No FTP HTTP

1. FTP transfers the file from client to

server and server to client.

HTTP transfer the file from server to

client.(i.e. web pages)

2. It uses two different port

connections. (i.e. port 20 and port

21)

HTTP use only one port connection.

(i.e. Port 80)

3. Uses TCP protocol. It also use TCP protocol.

11. List the two types of DNS message.

DNS messages are: Query and Response. The query message consists of the header

and the question records. The response message consists of a header, question record,

answer record, authoritative record and additional record.

12. Define threats.

Information access threats intercept or modify data on behalf of users who should not have

access to that data. Service threats exploit service flaws in computers to inhibit use by

legitimate users.

13.What is meant by attack?

An attack on system security that derives from an intelligent threat: that is an

intelligent act that is a deliberate attempt to evade security services and violate the

security policy of a system.

14. What is use of digital signature? What are the basic functions of e-mail?

Data appended to, or a data unit that allows a recipient of the data unit to prove the

source and integrity if the data unit and protect against forgery. Basic functions of e-

mail: composition, Transfer, Reporting, Displaying, and Disposition.

15. What is a URL and web browser?

Uniform Resource Locator is a string identifier that identifies a page on the World

Wide Web. Web browser is a software program that interprets and displays the

contents of HTML web pages.

16. What is rlogin? What are the two methods of HTTP?

Remote login is used to login into remote system and access its contents.

Two methods of HTTP are GetMethod( ) and PostMethod( ).

17. What is the main difference between FTP & HTTP?

FTP – Out – of – band, HTTP – In – band.FTP uses two parallel TCP connections to transfer

a file. They are Control Connection and Data connection.

18. What are the advantages of stateless server of HTTP?

Because of the statelessness of HTTP, it need not remember any transaction,

request or response. This results in a very simple implementation without the need

for complex state machines.

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19. What is the use of MIME Extension?

MIME converts binary files, executed files into text files. Then only it can be

transmitted using SMTP

SMTP cannot transmit text data including national language characters. MIME translates all

these non ASCII codes to SMTP 7 bit ASCII code

Messages – more than certain size can be translated by MIME into SMTP acceptable size

20. Which protocol support email and give details about that protocol?

SMTP is a standard protocol for transferring mails using TCP/IP

SMTP standardization for message character is 7 bit ASCII

SMTP adds log info to the start (i.e.) path of the message

21. How will you categorize DNS.

Internet is divided into many top level domains. Each domain is divided into sub

domain and so on.Topmost domains are categorized into generic and countries.

Generic domain categories:

com- commercial

gov- US government

edu- educational

org- profile organization

mil- US military

net- network providers.

23.Name some of the country category

uk - United kingdom, sg -singapore

jp - Japan, in - India

24.What an application program of DNS does?

The application program interested in obtaining IP address of a domain name calls

a library program "Resolver". Resolver sends UDP packet to nearest DNS server

(local DNS server)

Local DNS server looks up domain name and returns IP address to resolver as in

previous part. Resolver returns IP address to application program.

25. Describe why HTTP is designed as a stateless protocol.

Maintaining state across request-response connections significantly increase the

initial interactions in a connection since the identity of each party needs to be established

and any saved state must be retrieved. HTTP is therefore stateless to ensure that the

Internet is scalable since state is not contained in the HTTP request/response pairs by

default.

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26. Give an example for hierarchy of name servers.

27. What are the tables containing name servers?

Name servers are {name, value, type, class, TTL}

28. Define MIB. MIB is a companion specification that helps that helps client indicate which piece of

information it wants to retrieve and also helps the server know which variable in memory to

read to satisfy the request. The MIB defines the specific pieces of information—the MIB

variables—that you can retrieve from a network node. The current version of MIB, called

MIB-II, organizes variables into 10 different groups.

29. Define WSDL.

Web services definition language.

<wsdl:data types>

<wsdl:message>

<wsdl:port>

<wsdl:binding>

<wsdl:services>

30. Define MEP.

Message exchange pattern (MEP) that gives the sequence in which the message has to be

transmitted including the fault message to be sent when an error disrupts the message flow.

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31. What are the features of SOAP protocol?

Soap Envelope

Soap Part

Soap header

Soap header

Soap header

Soap Proxy

XML

Soap Default

32. Define Session Control Protocol and mention the different categories.

Many multimedia applications need a protocol called the session control protocol. For

example, suppose that we wanted to be able to make IP-based telephone calls across the

Internet. Session control protocol provides a mechanism to notify the intended recipient to

expect such a call for example, by sending a message to some multimedia device that would

cause it to make a ringing sound. We would also be able to support features like call

forwarding, three-way calling,

and so on using SCP.

The protocols that have been defined include

■ SDP (Session Description Protocol)

■ SAP (Session Announcement Protocol)

■ SIP (Session Initiation Protocol)

■ SCCP (Simple Conference Control Protocol)

33. Define Session Initiation Protocol (SIP)

SIP is an application-layer protocol that resembles HTTP. However, it is designed with a

different

sort of applications in mind, and thus provides quite different capabilities than HTTP.

The capabilities provided by SIP can be grouped into five categories:

■ User location: determining the correct device with which to communicate to

reach a particular user

■ User availability: determining if the user is willing or able to take part in a

particular communication session

■ User capabilities: determining such items as the choice of media and coding

scheme to use

■ Session setup: establishing session parameters such as port numbers to be used

by the communicating parties

■ Session management: a range of functions including transferring sessions (e.g.,

to implement ―call forwarding‖) and modifying session parameters

34. What are the informations included in SDP?

SDP conveys the following information:

■ The name and purpose of the session

■ Start and end times for the session

■ The media types (e.g., audio, video) that comprise the session

■ Detailed information needed to receive the session (e.g., the multicast address

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to which data will be sent, the transport protocol to be used, the port numbers,

the encoding schemes)

35. Define peer-to-peer network.

A peer-to-peer network allows a community of users to pool their resources (content, storage,

network bandwidth, disk bandwidth, CPU), thereby providing access to larger archival stores,

larger video-audio conferences, more complex searches and computations, and so on, than

any one user could afford individually.

For example, in the context of sharing MP3 files it means not having

to download music from a central site, but instead being able to access music files

directly from whoever in the Internet happens to have a copy of the required .mp3 file stored

on their computer.

PART B

1. Discuss how the Simple Mail Transfer Protocol (SMTP) is useful in electronic mail.

2. Describe about the World Wide Web (WWW).

3. What is Domain Name Service (DNS) and explain in detail about the domain

hierarchy and name servers.

4. Discuss about MIME, IMAP and POP3

5. Explain about HTTP.

6. Explain the SMTP and HTTP . Give their uses, state strengths and weaknesses.

7. Explain The role Of DNS in computer network

8. what is the idea used in public key encryption systems

9. Explain the salient Features of the SMTP protocol

10. Discuss about the components of network Management on the Internet

11. Write short notes on symmetric –Key –cryptography

12. How does the E-Mail system Work?

13. Explain in detail about WWW.

Note

All u can refer some problems based, what I taught in the class.

CS2363 EE Question+Bank

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