Networking Sq

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Explain the services provided by IP (Internet Protocol) - Addressing, Fragmentation, Packet timeouts andoptions

1. Addressing: For the purpose of delivering datagram packets, IP needs to know about the address of the destination. By includingthe host addressing, this task is carried out by IP. As IP operates in an internet, its systems are designed to accept the addressing of devices which are unique.

2. Fragmenting: The datagram packets are sent to the data link layer for the purpose of transmission on the network. The physicalnetwork frame size that uses IP may be different. To resolve this, IP fragments the datagram into certain pieces. So that, each piece

can be carried on the network. The receiving systems use these pieces and reassemble the whole IP datagram again.

3. Packet timeouts: A timeout packet is the time for waiting next instruction from the command station. If the command is not sent bythe station, it shuts down.

Explain the classes of IP address

IP addresses are organized into classes. For convenience of humans, IP addresses are expressed in the decimal format. Every number in each class is represented as binary to computers.

The four numbers in an IP address are known as octets. Each of them has eight bit positions. The octets are divided into two sections:Net and Host. The first octet represents Net for identifying the network and the Host contains the last octet. There are five IP classes.

Class A: The class A is used for very large networks. There are 1 to 126 are part of this class. That means there are 126 Class Anetworks. Class A networks accounts for half of the total available IP addresses.

Class B: It is used for medium size networks. The IP address with a first octet from 128 to 191 is part of this class. Class B networkshave a first bit value of 1 and a second bit value of 0 in the first octet.

Class C: Class C is used for small to middle size networks. IP address with a first octet starts from 192-223. Class C networks have afirst bit value of 1, second bit value of 1 and a third bit value of 0 in the first octet.

Class D: It has first, second and third bit value as 1 and the fourth bit as 0. The other 28 bits are used for identifying the group of computers which is intended for multicast messages.

Class E: Class E is used for identification purpose. The four bits value is 1. The other 28 bits are used for identifying the group of computers which is intended for multicast messages

Define Broadcast, Unicast and Multicast.

Unicast: A term used in communication to describe a piece of information to send from one point to another. There are only sender andreceiver. All LANs support unicast transfer mode and most applications that employ TCP transport protocol uses unicast messaging.

Broadcast: A term used for describing communication that is sent a piece of information from one point to all other points. There is onesender and multiple receivers. All LANs support broadcast transmission.

Multicast: A term described in communicating a piece of information sent from one or more points to a set of other points. The sendersand receivers are one or more.

What is Network Mask?

A network mask is used for determination of what subnet an IP address belongs to. An IP address has network address and the hostaddress. The first two numbers represents the network address and the second two numbers represents the host of the network.

Define Subnetting.

A subnet describes a set of networked computers which have common IP address routing prefix.


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Breaking the networking into smaller and more efficient subnets is known as subnets. Subnetting prevents Ethernet packet collisionwhich has excessive rates in a large network. Routers are used to manage the traffic and constitute borders among subnets.

What is the User Datagram Protocol (UDP)?

User datagram protocol allows computer applications to send messages as datagram packets from source to destination on an InternetProtocol, with out using prior communications for setting up special transmission paths. An unreliable service is provided by UDP whichmakes the datagram packets may arrive irrespective of order. UDP is a better solution for time-sensitive applications due to the reasondropping packets is preferable to use delayed packets. Its stateless nature makes the server to answer smaller queries to huge

number of clients.

What is TCP windowing concept?

TCP windowing concept is primarily used to avoid congestion in the traffic. It controls the amount of unacknowledged data a sender cansend before it gets an acknowledgement back from the receiver that it has received it.

What are the different types of VPN?

R emote Access VPN :- Also called as Virtual Private dial-up network (VPDN) is mainly used in scenarios where remoteaccess to a network becomes essential. Remote access VPN allows data to be accessed between a companys privatenetwork and remote users through a third party service provider; Enterprise service provider. E.g Sales team is usually presentover the globe. Using Remote access VPN, the sales updates can be made.

Site to Site VPN Intranet based: This type of VPN can be used when multiple Remote locations are present and can bemade to join to a single network. Machines present on these remote locations work as if they are working on a single network.

Site to Site VPN Extranet based: This type of VPN can be used when several different companies need to work in a sharedenvironment. E.g. Distributors and service companies. This network is more manageable and reliable.

What are the different authentication methods used in VPNs?

The authentication method uses an authentication protocol. The methods are:

EAP authentication method: Extensible authentication protocol authenticates remote access connection. The authenticationmechanism is decided between the remote VPN client and authenticator (ISA). The mechanism is typical in whichauthenticator requests for authentication information and the responses are given by the remote VPN client.

MS Chap Authentication method: Microsoft Challenge Handshake Authentication Protocol (MS-CHAP) starts with theauthenticator (Remote access server) challenge. The challenge to the remote access client sends a session identifier andchallenge string. The client in response sends the nonreversible encryption of the string, the identifier and password.

Authenticator checks the credentials and grants access on a successful authentication. Unencrypted passwords (PAP) :- Uses plain text passwords. Does not involve encryption. Used for less secure clients. Shiva Password Authentication Protocol (SPAP) :- It is a password authentication protocol. It is less secure as the same

user password is always sent in the same reversibly encrypted form

What is Tunneling?

Tunneling is a mechanism provided to transfer data securely between two networks. The data is split into smaller packets and passedthrough the tunnel. The data passing through the tunnel has 3 layers of encryption. The data is encapsulated. Tunneling can beapproached by Point to Point tunneling protocol.

What are voluntary and compulsory tunnels?

Voluntary Tunneling Users computer is an end point of the tunnel and acts as tunnel client. Here the client or user issues a request to configure and create avoluntary tunnel. They require a dial up or LAN connection. Example of dial up connection is internet at home where a call is made tothe ISP and connection is obtained.

Compulsory tunneling In compulsory tunneling, instead of the user a vpn remote access server configures and creates a tunnel. Hence, the end point is theRemote sever not the user.


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Explain static and dynamic tunnels.

Tunnels that are created manually are static tunnels. Tunnels that are auto discovered are dynamic tunnels. In dynamic tunneling, tcpconnections can be checked dynamically. If no connections exist that are routed through the tunnel, a check for more suitable gatewaycan be done. Static tunneling may at times require dedicated equipments.

Explain the importance of increasing and decreasing subnet bits.

Adding 1s as a bit means increasing the subnets and decreasing the hosts. Removing or decreasing 1s means decreasing subnets

and increasing hosts. Hence by increasing or decreasing the subnet architecture can be decided as per needs.

What is R TP?

Real-Time Transfer Protocol lays a standard or a way to transfer or manage real time data over a network. It does not guarantee thedelivery of data or provide any quality of service. However it helps to manage the data. Which means that RTP can be used deliver thenecessary data to the application to make sure it can put the received packets in the correct order Real time data examples could beaudio and video.

What is R TP Multiplexing?

RTP multiplexing allows multiple media flows within a single RTP data payload between two points. This means that it can be used tocarry multiple streams of data in one RTP packet. RTP multiplexing will reduce the bandwidth used. RTP multiplexing will also increasescalability.

Explain the use of R TP and R TCP protocols.

Use of RTP and RTCP:-

1. RTP can be used to transfer Real time data like voice packets.2. RTP can be used with RTCP which makes it possible to monitor data.3. Packet loss can be detected by RTP using Sequence number

RTCP provides Qos feedback :- Packets lost, round trip time.

Describe the format of R TP and R TCP packets.

The 32 bits of RTP packet format is as follows:- (L to R)

Bit 0-1:- Indicates version, currently 2Bit 2:- P- indicates padding bytesBit 3:- X- Indicates presence of extension header Bit 4-7:- CC- Contains number of CSRC identifiers that follows the header Bit 8:- M- Current data has some special relevance (if set)Bit 9-15:- PT- Indicates format of payloadBit 16-31:- Sequence number Timestamp: - 32bits time stamp of packetSSRC- Synchronization source identifier uniquely identifies the source of a stream.CSRC -Contributing source IDs enumerate contributing sources to a stream which has been generated from multiple sourcesExtension header: - first 32 bit word contains profile specific identifier and length specifier

The 32 bits of R TCP header format is as follows:- (L to R )Bit 0-1:- Indicates version, currently 2Bit 2:- P- indicates padding bytesBit 3 to 7:- Count of number of reception report blocksBit 8 to 15:- Type: - Determined RTCP packet type. Type can take values from 0 to 25516 to 31:- Length- Length of RTCP packet - 1SR: - Sender Report for transmission and reception from active sendersRR: - Receiver report for reception from in active sendersSDES: - Source description items


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BYE- indicates end of participation APP: - Application specific functions

Describe how the multicast protocol works.

Multicast protocol or Internet protocol delivers a singles message to multiple machines. One packet from the source is replicated andsent to the destination. Every multicast message requires a multi case group. The group defines the addresses which will receive themessage. The group is defined by the class D address. Different routing protocols are used to find the multicast groups and build routesfor them. Distance Vector Multicast protocol is one of them. The receiver, to whom the multicast packet is sent to, needs to join the

group. Joining the group is enabled and managed by IGMP. Multicast routers are used to transmit the messages from one network toanother.

Describe how to control the scope of multicast transmissions.

Controlling the scope of multicast transmission restricts the range of group members. TTL (Time To Live) is one of the mechanisms tolimit the scope. If the TTL value is small, packets would only be multicast to smaller distance destinations. More the value of TTL, morewould be the scope of transmission to a larger number of machines. Administrative scoping is another mechanism. In this, transmissionis restricted to a specific address space of an organization or a site.

Explain why use Multicasting.

When the same message or packet needs to be sent to multiple destinations, multicasting is used. Within campus and offices, using multicasting file distribution can be done. System messages, news and videos can be sent at the same time. More commonly used for audio and video streaming.

What are Sockets? How do Sockets Work?

A socket is used to connect an application to a network protocol. A socket enables communication between a client and a server. Thecommunication is started when the client is assigned a local port number, and binds a socket to it. The client writes on the socket andgets information from server by reading it.

The Socket class is used to communicate. It provides rich set of methods for both asynchronous and synchronous data transfer.ConnectAsynch is used to start an asynchronous connection. SendAsynch and ReceiveAsynch are used to send and receive data.Shutdown and close methods are used to shutdown and close the sockets.

Datagram vs. stream.

Stream can be considered as a pipe that allows full duplex connection. A datagram or a packet on the other hand, has a source and adestination. There is no connection. Stream is like a communication channel while datagram is completely self contained. Streamsprovide a reliable and sequenced communication. Datagrams on the other hand are unreliable and no sequence maintained.

What is a stream socket?

A stream socket provides two way communications between a client and server. This communication is reliable and sequenced. Streamsockets are above TCP to run across any networks. They provide unduplicated flow of data and have well established mechanism for creating and destroying connections and for detecting errors.

What is SSL?

SSL is Secured Socket Layer. SSL is used to establish a secured and an encrypted connection between a server and the browser. SSLis most commonly seen in payment and banking web sites. To create a SSL connection, a SSL certificate needs to be created. If thewebsite has a SSL certificate installed, a small icon is displayed in the tool bar to make customers confident that the site is secured.

What are the two important TCP Socket classes? Explain them

The two most important socket Classes are:


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Socket Class: The Socket class provides enriched methods and properties for network communications. It allows bothsynchronous and asynchronous data transfer. Shutdown method should be used to end the Socket once the data transfer iscomplete. Using SetSocketOption the socket can be configured.Declaration:

Public Class Socket _ Implements IDisposable

Server Socket Class: The server Socket class is used to implement server sockets. Server sockets are used to respond torequests received over the network.

What are the advantages and disadvantages of Java Sockets?

Advantages:

Flexible and powerful. Cause low network traffic if efficiently used. Only updated information can be sent.

Disadvantages:

The Java applets can establish communication only with the machine requested and not with any other machine on thenetwork.

Sockets allow only raw data to be sent. This means that both client and server need to have mechanisms to interpret the data.

What is race condition? How does the race condition occur?

A race condition occurs when there are two or more processes trying to access the same data concurrently or performing the sameoperation concurrently. Output of the operation depends on the sequence of requests of the operations.

In networking, a race condition occurs when two or more try to access the same channel. This usually occurs in networks having lagtimes.

In a computer memory, a race condition occurs when a request to read and write data is received at the same time.

In logic gates, a race condition occurs when some inputs encounter conflicts.

What is meant by Symmentric Multiprocessing (SMP)?

Symmetric Multiprocessing allows any processor to do work of another processor. SMP allows multiple processors to process programsthat are a part of common OS and memory. Most common example of SMP is OLTP where many users access the same database in arelatively simple set of transactions. SMP efficiently balances the workload of the processors.

What are TP-Lite and TP-Heavy Monitors?

TP Lite is an integration of TP Monitor functions in a database engine. TP-Heavy Monitor allows the machine to initiate some complexmulti server transactions. TP Heavy monitors support client server architecture.

What is the Domain Name System (DNS)? What are the advantages of it?

A hierarchical naming system for computer systems, services or for that matter any resource participating in the internet. Variousinformation with domain names is assigned to each of the participants. DNS translates the names of domain into meaningful to humansinto binary identifiers that are associated with the equipment of network to locate and address these devices.

Advantages:

More R eliable: Delivers messages to the users with zero downtime.


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Faster: DNS are connected well at intersections of internet. Any cast technology enables requests are answered to the next closestnode in the case of maintenance or downtime.

Smarter: Automatic corrections of typos.

What is the TTL (Time to Live)? Why is it required?

TTL is a value in data packet of Internet Protocol. It communicates to the network router whether or not the packet should be in thenetwork for too long or discarded. Usually, data packets might not be transmitted to their intended destination within a stipulated period

of time. The TTL value is set by a system default value which is an 8-bit binary digit field in the header of the packet. The purpose of TTL is, it would specify certain time limit in seconds, for transmitting the packet header. When the time is exhausted, the packet wouldbe discarded. Each router receives the subtracts count, when the packet is discarded, and when it becomes zero, the router detects thediscarded packets and sends a message, Internet Control Message Protocol message back to the originating host.

Explain the use of Internet Control Message Protocol (ICMP).

Internet Control Message Protocol is one of the important protocols in the Internet Protocol suite. It is mainly used in operating systemof networked computers, for the purpose of sending error messages, for example, a requested service is unavailable or the host couldnot be reached. It is not directed by the network applications. ICMPs are utilized by routers, hosts for communicating the updates or error information to other routers.

What is the use of IGMP protocol?

Internet Group Management Protocol: - It allows internet hosts to participate in multicasting. The IGMP messages are used to learnwhich hosts is part of which multicast groups. The mechanism also allow a host to inform its local router, that it wants to receivemessages.

What are Ping and Tracert?

Ping and tracert are the commands used to send information to some remote computers to receive some information. Information issent and received by packets. Ping I particularly used to check if the system is in network or not. It also gives packet lost information. Inwindows ping command is written as ping ip_address Tracert is called as trace route. It is used to track or trace the path the packettakes from the computer where the command is given until the destination. In windows ping command is written as tracert ip_address

Explain R SVP. How does it work?

Resource Reservation protocol is used to reserve resources across a network. It is used for requesting a specific Quality of Service(QoS) from the network. This is done by carrying the request (that needs a reservation of the resource) of the host throughout thenetwork. It visits each node in the network. RSVP used two local modules for reservation of resources. Admission control moduleconfirms if there are sufficient available resources while policy module checks for the permission of making a reservation. RSVP offersscalability. On a successful completion of both checks RSVP uses the packet classifier and packet scheduler for the desired Qosrequested.

Explain the concept of DHCP.

Dynamic Host Configuration Protocol is used assigning IP addresses to computers in a network. The IP addresses are assigneddynamically. Certainly, using DHCP, the computer will have a different IP address every time it is connected to the network. In some

cases the IP address may change even when the computer is in network. This means that DHCP leases out the IP address to thecomputer for sometime. Clear advantage of DHCP is that the software can be used to manage IP address rather than theadministrator.

What are the differences between a domain and a workgroup?

In a domain, one or more computer can be a server to manage the network. On the other hand in a workgroup all computers are peershaving no control on each other. In a domain, user doesnt need an account to logon on a specific computer if an account is availableon the domain. In a work group user needs to have an account for every computer.In a domain, Computers can be on different local networks. In a work group all computers needs to be a part of the same localnetwork.


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Explain how NAT works.

Network Address Translation translates and IP address used in a network to another IP address known within another network. A NATtable is maintained for global to local and local to mapping of IPs. NAT can be statically defined or dynamically translate from a pool of addresses. The NAT router is responsible for translating traffic coming and leaving the network. NAT prevents malicious activityinitiated by outside hosts from reaching local hosts by being dependent on a machine on the local network to initiate any connection tohosts on the other side of the router.

What is PPP protocol? Explain PPP packet format.

Point to Point protocol helps communication between 2 computers over a serial cable, phone line or other fiber optic lines. E.g.Connection between an Internet Service Provider and a host. PPP also provides authentication. PPP operates by sending Requestpackets and waiting for Acknowledge packets that accept, reject or try to change the request. The protocol is also used to negotiate onnetwork address or compression options between the nodes.

Packet format:-

Flag field: 1 byte: - Indicates frames beginning or end Address field: 1 byte: - Used for broadcast address (destination address)Control field: 1 byte: - Used as a control byteProtocol field: - 1 or 2 bytes: - Setting of protocol in information field (of datagram)Information: - 0 or more bytes: - Datagram (whether it contains data or control information)

Padding: - 0 or more bytes: - optional paddingFCS: - 2 or more bytes: - error check sum

What is IP Spoofing and how can it be prevented?

IP spoofing is a mechanism used by attackers to gain unauthorized access to a system. Here, the intruder sends messages to acomputer with an IP address indicating that the message is coming from a trusted host. This is done by forging the header so itcontains a different address and make it appear that the packet was sent by a different machine.

Prevention:-Packet filtering: - to allow packets with recognized formats to enter the networkUsing special routers and firewalls.Encrypting the session

Explain IP datagram, Fragmentation and MTU.

IP datagram can be used to describe a portion of IP data. Each IP datagram has set of fields arranged in an order. The order is specificwhich helps to decode and read the stream easily. IP datagram has fields like Version, header length, Type of service, Total length,checksum, flag, protocol, Time to live, Identification, source and destination ip address, padding, options and payload.

MTU:- Maximum Transmission Unit is the size of the largest packet that a communication protocol can pass. The size can be fixed bysome standard or decided at the time of connection

Fragmentation is a process of breaking the IP packets into smaller pieces. Fragmentation is needed when the datagram is larger thanthe MTU. Each fragment becomes a datagram in itself and transmitted independently from source. When received by destination they

are reassembled.

What is an application gateway?

An application gateway is an application program that runs on a firewall between two networks. An application gateway is used for establishing connection between client program and destination service. The client negotiates with the gateway to communicate withthe service of destination. Here, gateway can be called as a proxy. Hence, two connections are made. One between client and proxy;other, between proxy and destination service. Connections take place behind the firewall


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Session Layer

Controls the connections between computers Establishes, manages and terminates the connections between the local and remote application. Provides full-duplex, half-duplex, or simplex operation Establishes checkpointing, adjournment, termination, and restart procedures

Transport Layer:

Provides transparent transfer of data between end users Providing reliable data transfer services to the upper layers Controls the reliability of a given link through flow control, segmentation / desegmentation, and error control.

Network Layer

Provides the functional and procedural means of transferring variable length data sequences from a source to a destination viaone or more networks

Performs networkrouting functions Performs fragmentation and reassembly, and report delivery errors.

Data Link Layer

Provides the functional and procedural means to transfer data between network entities Detects and corrects errors that occur in the Physical Layer.

Physical Layer:

Defines the electrical and physical specifications for devices.

What is VLSM, Variable length subnet masking?

VLSM is a means of allocating IP addressing resources to subnets according to their individual need rather than some general network-wide rule.

Explain the concepts and capabilities of IP Datagram.

Data transmitted over an internet using IP is carried in messages called IP datagrams.Like all network protocol messages, IP uses a specific format for its datagrams.

The IPv4 consists of the following fields:

Version: the version of IP used to generate the datagram. For IPv4, this is of course the number 4 Internet Header Length: Specifies the length of the IP header, in 32-bit words. Type of service: information to provide quality of service features Total Length Identification: it can be used if the datagram must be fragmented by a router during delivery and then for reassembling. Flags: (Dont Fragment, More Fragment) Fragment Offset: When fragmentation of a message occurs, this field specifies the offset, or position. Time to Live: specifies how long the datagram is allowed to live Protocol: ICMP, TCP, UDP, etc Header Checksum: to provide basic protection against corruption in transmission. Source Address Destination Address Options Padding: if number of bits used for options is not a multiple of 32, then padding is added Data


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What is Bluetooth?

Bluetooth is a wireless technology standard used to exchange data over short distances. The data is exchanged from fixed and mobiledevices by creating Personal Area Network with security at high level. Bluetooth was originally conceived as a wireless alternate to RS-232 cables. It resolves the problems synchronization by connecting several devices.

Bluetooth is called a cable replacement technology. Explain.

Blue tooth allows Personal Area Networks without the cables. It provides connectivity to many mobiles users at a time for sharingwithout wires. Blue tooth chip is designed for replacing cables by transmitting the information at a special frequency from sender toreceiver.

What is R J-45?

RJ-45 stands for Registered Jack 45. It is an 8-wire connector for connecting computer systems on to a LAN, especially Ethernets.These connections are similar in appearance to the ubiquitous RJ-11, which are used in connecting telephone equipment, with littlemore width.

What is the signal strength transmitted by cell phones?

The magnitutude of the electric field at a reference point, which is significant distance from the transmitting antenna, is known as signalstrength. Signal strength is expressed in voltage/length or signal power received by the antenna. In mobile phones, the signal strengthis usually expressed in dB-microvolts per meter or in decibels above a reference level of one milliwatt.

What are Bluetooth profiles?

In order to describe the way of implementing user models accomplishments, the profiles are developed. A number of user scenarios aredescribed by the user models where Bluetooth performs the radio transmission. Profile stack describes the options in each protocolwhich are mandatory for each profile, and defines range of parameters for each protocol. The profiles are concerned for decreasing therisk of interoperability issues among various products of different manufacturers.

What are the technical characteristics of Bluetooth?

The following are the technical characters of a Bluetooth device:

The devices are either a one chip solution or multiple chips in general. Blue tooth device has three main parts RF, basebandprocessor and link manager (could be a CPU core like 8 or 16 bit Reduced Instruction Set Computer. A BT module in multiple chips,usually 2 or 3 chip, like RF on a chip are produced by certain vendors.

For a single chip solution, the following information can be used for referencing from a particular vendor.

Package - 81 ball BGA, 8mm x 8mmSupply Voltage - 2.7 3.3vPower Consumption - Data transmitting @ 4dBm type 41mA

Voice Only Connection - 15mA for HV3 packets, 30mA for HV1RI Page Scanning - 420uAInquiry Scanning + RI Page Scanning - 560uAPark mode (1 second interval) - 120uAStandby state - 10uA

The components, the chip, memory and the crystal, antenna could be placed on a PCB about 20mm x 15mm. The thickness of the chipis about 1.25mm or 1.55 mm..

What is Cabir Worm? Which devices does the Cabir Worm affect?

A Cabir worm is one of the malicious software, usually referred as malware. It utilizes Bluetooth technology for sending itself to another similarly vulnerable device. As it is self-replicative, is it classified as a worm.


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Passive FTP: The client initiates the connections to the server and solving the problem of firewalls filtering the incoming data portconnection to the client from the server is done in passive FTP mode. The client opens two random unprivileged ports locally onopening an FTP connection. The server is contacted on the first port, 21. Instead issuing a PORT command and allowing the server for connecting back to its data port, the command PASV is issued by the client. The server opens a random unprivileged port and sendsthe PORT P command back to the client. The connection from port N+1 to port P on server to transfer data is initiated by the client.

Explain the concepts of digital certificates.

A digital certificate is a credential which validates the certificate owners identity. The information provided by the digital certificate is

known as the subject distinguished name. Certificate Authority issues the digital certificates to the users or the organizations. The trustin the certificate as a valid credential is provided as the foundation by the Certificate Authority.

What is Maximum Transmission Unit (MTU)?

Maximum Transmission Unit is the size of a layer of communication protocols of the largest protocol data unit which it can passonwards. In association with a communications interface such as NIC, serial port etc., MTU parameters usually appears. The fixation of MTU can be done by standards like Ethernet or decided at the time of connection (usually in the case of point-to-point serial links).Greater efficiency is brought by higher MTU as more user data is carried by each packet while protocol overheads remain fixed. Bulkprotocol throughput improvement is referred as high efficiency. However, large packets can occupy a link that is slow for some time,which causes greater delays for the following packets and increases lag and minimum latency.

What is the network segmentation? What is Collision Domain?

Network segment is a portion in a computer network where communication among every device is done using the same physical layer.The networking segmentation can be either logical or physical.

A collision domain is a logical network segment. In this segment, data packets can collide to each other. Ethernet is the commonprotocol used when referring to a collision domain. Collision segment is a group of Ethernet devices in LAN, which runs on CSMA/CD,and is connected through repeaters for the purpose of competing network access. As data can be transmitted through one device in thesame collision domain, the other devices simply listens in the network in order to avoid data collisions. Carrier Sense Multiple

Access/Collision Detection (CDMA/CD) is an efficient way for avoiding network collisions.

Explain the functionality of a hub, a bridge and switch.

Hub: Hub is a device in a network, Data packet from one port is sent to all other ports in a network. The data packet passes through ahub. Hub transmits the data packet to the destination. Hubs are typically used on small networks where the data transmission is never high.

Bridge: A bridge is similar to hub but one step ahead. It looks for the destination of the packet before transmission of data. A bridgehas only one incoming and one outgoing port. A bridge is used to decide if the message should continue. Bridges are typically used for separating parts of the network which need not communicate regularly, but obviously needs to be connected.

Switch: A switch is similar to bridge but one step ahead. A packet is determined to which computer the packet is sent. Efficiency isincreased in this way of data packet transmission only to the destined computers but not all. Large networks use switches to connectcomputers within in the same subnet.

What is R AID?

The core concept of Redundant Array of Independent Disks is two or more drives are combined together for improvement of performance and fault tolerance. Improved reliability and large data volumes are offered by combining two or more drives. Data spreadsacross many disks by RAID and operating system treats this array as a single disk.

Difference between terminal services and remote desktop.

Terminal service is a client-server environment. In this environment, one computer acts as a server which receives requests from theclients. The servers can serve in two modes Application Server mode and Remote Administration mode. The applications on theserver are accessed by the former and the later is utilized for remote administration. R emote desktop simulates the terminal services of Remote Administration Mode. The difference is there is no client-server environment. Remote desktop is simply used for the purpose of sharing one computers desktop in a network.

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