CCNA1

Final Exam Review

Binary / Hexadecimal

Conversion

Binary Hex Binary Hex

0000 00 1000 08

0001 01 1001 09

0010 02 1010 0A

0011 03 1011 0B

0100 04 1100 0C

0101 05 1101 0D

0110 06 1110 0E

0111 07 1111 0F

Hexadecimal / Decimal Conversion

Hex Dec

01 161 x 0 + 160 x 1 = 0 + 1 = 01

09 161 x 0 + 160 x 9 = 0 + 9 = 09

0A 161 x 0 + 160 x 10 = 0 + 10 = 10

0F 161 x 0 + 160 x 15 = 0 + 15 = 15

10 161 x 1 + 160 x 0 = 16 + 0 = 16

11 161 x 1 + 160 x 1 = 16 + 1 = 17

19 161 x 1 + 160 x 9 = 16 + 9 = 25

1A 161 x 1 + 160 x 10 = 16 + 10 = 26

1F 161 x 1 + 160 x 15 = 16 + 15 = 31

20 161 x 2 + 160 x 0 = 32 + 0 = 32

2F 161 x 2 + 160 x 15 = 32 + 15 = 47

30 161 x 3 + 160 x 0 = 48 + 0 = 48

FF 161 x 15 + 160 x 15 = 240 + 15 = 255

Determine Subnet Address from

IP Address and Subnet MaskDetermine the subnet address of host 130.30.2.40 255.255.255.224

Number of Subnets = 211 = 2048 (borrowing 11 bits - 3bits from 4th octet)

Magic Number = 256 – 224 = 32 or 2 host bits = 25 = 32

Subnet Addresses - (0.0) and (255.224) are not usable

(0.0) 0.32 0.64 0.96 0.128 0.160 0.192 0.224 (note: 224 = 11100000)

1.0 1.32 1.64 1.96 1.128 1.160 1.192 1.224

2.0 2.32 2.64 2.96 2.128 2.160 2.192 2.224

3.0 3.32 3.64 3.96 3.128 3.160 3.192 3.224

…

255.0 255.32 255.64 255.96 255.128 255.160 255.192 (255.224)

The host with address 130.30.2.40 is on Subnet 130.30.2.32

Determining the Proper

Subnet MaskBits Usable Remaining Usable

Class Borrowed Subnets Host Bits Hosts

A 2 – 22 2- >4M 22 – 2 >4M - 2

B 2 – 14 2 – 16382 14 – 2 16382 - 2

C 2 – 6 2 – 62 6 – 2 62 – 2

Number of subnets = 2x – 2, where x = number of bits borrowed

Number of hosts = 2x – 2, where x = number of remaining host bits

222 – 2 = 4,194,304 – 2 = 4,194,302

Class C Subnetting Chart

Slash format /25 /26 /27 /28 /29 /30

Mask 128 192 224 240 248 252

Bits Borrowed 1 2 3 4 5 6

Value (weight) 128 64 32 16 8 4

Total Subnets 4 8 16 32 64

Usable Subnets 2 6 14 30 62

Total Hosts 64 32 16 8 4

Usable Hosts 62 30 14 6 2

9.2.6 Public and private IP addresses

9.2.4 Class A, B, C, D, and E IP addresses

9.2.4 Class A, B, C, D, and E IP addresses

16 Class-B networks

1 Class-A network

256 Class-C networks

9.2.8 IPv4 versus IPv6

Calculating Data

Transmission Times

Bandwidth is measured in Mbps

File Size is usually measured in Mbytes

Must convert Mbytes to Mbits

Mbits = Mbytes * 8

Time to transmit = file size * 8 / bandwidth

Transport Layer Features

•TCP is a connection oriented, reliable transport protocol

that implements flow control and error correction

•Three-way handshake, Sequence numbers, windows,

and expectational acknowledgments

•UDP is a connectionless, unreliable transport protocol that

runs over reliable networks. It is considered very efficient

because it has little overhead compared with TCP. It does

not use sequence numbers or windowing, and is considered

a best effort delivery protocol that does not do error

correction.

Properties of Electric Charges

and Electric Forces

•Atoms are composed of neutrons (neutral

charge), electrons (negative charge) and protons

(positive charge).

•It is generally assumed that current flows from a

negative to a positive due to the flow of electrons

in materials that have an abundance of free

electrons.

•Unlike charges attract one another

•Like charges repel one another

Conductors, Insulators and

Semiconductors•Conductors are materials that allow the free flow of electrons

under the influence of a potential difference across the

material. Materials include copper, silver, gold, aluminum,

lead, tin, etc. (Most metallic materials are conductors,

although some are better conductors than others.)

•Insulators are materials that do not support the flow of

electrons. In other words, they don’t have free electrons.

Materials include plastics, wood, glass, etc.

•Semiconductors are materials that have special properties

that allow them to control the flow of electrons. They may

behave as conductors or insulators depending on external

stimuli. Materials include silicon, germanium, selenium, etc.

Characteristics of

AC and DC Voltages

•DC voltages have unchanging polarities

•DC voltage causes current to flow in one direction, from

negative to positive.

•AC voltage reverses its polarity, changing in a sinusoidal

manner from positive to negative and back to positive during

every cycle. Each cycle is called a period and the inverse of

the period is called the frequency of the signal.

•AC voltages are normally used to carry power through

transmission lines, because it can be delivered efficiently

over large distances.

Testing Cable for its Information

Carrying Capacity•Attenuation factors are important in determining whether a

particular cable type will be suitable for carrying signals of a

particular bandwidth. Attenuation generally increases as

frequencies increase. A cable that works at low frequencies

or in low bandwidth applications may not be suitable for

high frequency, high bandwidth applications.

•Attenuation is affected by a cables physical characteristics,

including its dimensions and materials used in its

construction. Its resistance, capacitance and inductance

affect its attenuation (loss in signal strength over distance).

•A cables analog bandwidth is measured in MHz and

determines its ability to work in a particular application.

High Speed Ethernet

Implementation

•1Gbps, 10Gbps or 100Gbps implementations are still

expensive compared to low speed Ethernet alternatives

(100baseTX).

•Generally they are not used in connectivity between

workstations or between workstations and backbone switches.

•They are used extensively to interconnect backbone switches,

servers, and access links.

Router Connectivity

Interface Cable Type

•Console Port (RJ45) Rollover cable

•Serial (DB60) Serial cables (DCE or DTE)

•Ethernet (RJ45) Cat 5, Cat 5e, Cat 6

•Ethernet (AUI) Transceiver to RJ45/coaxial

(Attachment Unit Interface) connector (transmitter/receiver)

ISDN Channels

•ISDN base rate interface (BRI) – Integrated Services Digital

Network (128Kbps 2B+D, dial-on-demand (DOD) service)

•2 B-channels - 64Kbps channels for data transmission

•1 D-channel - 16Kbps channel for control and signaling

information

•ISDN primary rate interface (PRI) - Integrated Services

Digital Network (1.544Mbps T1 23B+D service)

•23 B-channels – 64Kbps channels

•1 D-channel – 64Kbps channel

Common Features of

100BASE Technologies

•100BaseTX, 100BaseFX

•Frame formats are identical

•Timing is identical

•Both use multi-stage encoding (1st level encoding, followed

by line encoding)

•Both use 4B/5B as a first level encoding scheme

•TX uses multilevel transmit 3 (MLT-3) line encoding

•FX uses NRZI line encoding

Gigabit Speeds on Cat 5e Cable

( 1000BASE-T )

•Complex task on Cat5e cable

•Cat5e can carry up to 125Mbps over a single wire pair

•1000Base-T uses of all four pairs of wires in full-duplex

mode, simultaneously.

•Full-duplex transmission on the same wire pair allows

250Mbps per pair; multiply this by 4 pairs gives a total of

1000Mbps.

•Uses 8B1Q4 encoding with 4D-PAM5 line encoding.

Applications of

Standard Ethernet

•Interior cabling of buildings (inter-building connections)

•Vertical wiring (patch cables)

•Horizontal wiring (wiring in ceilings from workstations outlets

to wiring closets)

Effects of Adding Hubs

•Increases the size of the collision domain, but only a single

collision domain exists.

•Decreased bandwidth

•Increased the chance of collisions

•Decreased network performance

TCP/IP Applications

and Protocols

•Telnet Application service that allows you to login to a

remote server

•FTP, TFTP Applications used for file transfer

•PING Application that allows you to check

connectivity

•ARP Protocol that broadcasts an arp request to obtain

a MAC address that matches a given IP address

•Proxy ARP Feature implemented on a Router whereby the

router responds to the ARP request with its own MAC address,

if the broadcast is for a host that does not exist on the local lan.

TCP and UDP Port NumbersPort Numbers range from 0 – 65535 (numbers below 1024 are considered

well-known port numbers)

Application Layer Transport Layer Port Numbers

FTP data 21

FTP control 20

Telnet 23

SMTP (Simple Mail Transport Protocol) 25

DNS (Domain Name System) 53

TFTP (Trivial File Transfer Protocol) 69

SNMP (Simple Network Management Protocol) 161

HTTP (Hypertext Transfer Protocol) 80

POP3 (post office protocol ver 3) 110

IMAP4 (Internet Message Access Protocol) 993

FTP Port Assignments

Connection oriented file transfer

ftp-data 20/tcp File Transfer [Default Data]

ftp 21/tcp File Transfer [Control]

FTP can be used to transmit either ASCII or binary

information between a server and a local client

running FTP

Separate port numbers are used for communicating

control information and data.

Replacing Hubs with Switches

•Causes segmentation (micro-segmentation) of the LAN into

separate collision domains when the switch is configured for

Full duplex.

•Switches create separate collision domains but still only one

broadcast domain.

•No wiring changes required.

Reasons for

Excessive Broadcasts

•ARP requests are generated to get the MAC address that

matches a particular IP address.

•RIP updates – every router using rip broadcasts its complete

routing table to all of its neighbours every 30 seconds

•Video-Over-IP applications – Broadcast addresses are often

used to send information out to multiple hosts simultaneously.

Spanning Tree Protocol (STP)

•STP is used to eliminate switching loops from occurring on

Layer 2 networks

•STP constantly monitors switch ports so that the protocol

knows all links that exist in the network.

•When more than one link exists, STP disables the secondary

link(s) until needed. These redundant links are shut down,

putting a stop to any data loops in the network.

•The STP process elects a root bridge in the network that will

decide on the network topology. These can be only one root

bridge.The root bridge ports are called designated ports, and

these operate in what is called a forwarding state. Forwarding

ports send and receive traffic. (continued)

•The STA is used to determine the cost to assign to each link

based on bandwidth. The port that has the lowest cost to the root

bridge is called the root port, which sends and receives traffic.

•Ports that are determined to have the lowest-cost path to the

root bridge are also called designated ports and , like the root

bridge ports, they operate in forwarding state.

•Other ports on a bridge are considered nondesignated, and will

not send or receive traffic. This is called blocking mode.

•STP is enabled by default on on most Cisco switches with

Ethernet or Fast Ethernet ports.

•STP exchanges information using bridge protocol data units

(BPDUs).

(continued)

•The ports on a bridge or switch running STP can transition through four

different states:

•BLOCKING Won’t forward frames, listens to BPDUs. All ports are in

blocking state by default when the switch is powered up.

•LISTENING Listens to BPDUs to make sure no loops occur on the

network before passing data frames.

•LEARNING Learns MAC addresses and builds a filter table, but does not

forward frames.

•FORWARDING Sends and receives data on the bridge port.

•Once a switch determines the best path to the root bridge, that port

becomes the designated port, and all other ports will be put into blocking

state.

•If a switch determines that a blocked port should now be the designated

port, it will go into listening state. The port will check all incoming BPDUs

heard to make sure that the switch wouldn’t create a data loop if the port

goes into forwarding state.

8.1.6 Spanning-Tree Protocol

You must know the five STP states and their purpose.

8.1.6 Spanning-Tree Protocol

Function of each OSI LayerLayer 7 Application – Provides a user interface

Layer 6 Presentation – Presents data, Handles processing such as

encryption

Layer 5 Session – Keeps different applications data separate.

Layer 4 Transport – Provides reliable or unreliable delivery, performs error

correction and flow control. Data is broken into segments. (TCP, UDP)

Layer 3 Network – Provides logical addressing, which routers use for path

determination. Encapsulates segments into packets or datagrams. (Routers)

(IP)

Layer 2 Data Link – Combines packets into bytes and bytes into frames,

provides access to media using MAC addresses, performs error detection

but not correction. (switches, bridges)

Layer 1 Physical – Moves bits between devices, specifies voltage, wire

speed and pin-out of cables. (repeaters, hubs, media)

Routing Protocols

RIP ver 1.0 IGP distance vector (classful routing only)

RIP ver 2.0 IGP distance vector (classless)

IGRP IGP distance vector (proprietary)

EIGRP IGP hybrid (proprietary)

OSPF IGP link state routing protocol

IS-IS EGP link state routing protocol

BGP EGP link state – (border gateway protocol)

Know the difference between Routed vs Routing Protocols

IP is a routed protocol and all of the above are routing

protocols

Cat5e Cable Types

Straight-Through Standard (568a or 568b on both ends)

Switch or Hub to Router

Workstation to Switch or Hub

Cross-Over (568a on one end and 568b on the other end)

Switch or Hub to Another Switch or Hub

Workstation to Workstation (peer to peer)

Rollover (1-8 on one end goes to 8-1 on the other)

Router or Switch Console to PC Serial Port

•no electrical signals •no generation of electromagnetic waves

Fiber has no Xtalk

•Xtalk is another form of noise

•CAT 5e & 6c

•light waves on optical fiber •radio waves in the air

The Power budget or Link budget(Watts,Volts,dB)

802.11b

802.11b may also be called Wi-Fi™ or high-speed wireless and refers to DSSS systems that operate at 1, 2, 5.5 and 11 Mbps.

All 802.11b systems are backward compliant in that they also support 802.11 for 1 and 2 Mbps data rates for DSSS only. This backward compatibility is extremely important as it allows upgrading of the wireless network without replacing the NICs or access points.

802.11b devices achieve the higher data throughput rate by using a different coding technique from 802.11, allowing for a greater amount of data to be transferred in the same time frame.

The majority of 802.11b devices still fail to match the 11 Mbps throughput and generally function in the 2 to 4 Mbps range.

802.11a

802.11a covers WLAN devices operating in the 5 GHZ transmission band.

Using the 5 GHZ range disallows interoperability of 802.11b devices as they operate within 2.4 GHZ.

802.11a is capable of supplying data throughput of 54 Mbps and with proprietary technology known as "rate doubling" has achieved 108Mbps.

In production networks, a more standard rating is 20-26 Mbps.

802.11g802.11g provides the same throughout as 802.11a but with backwards compatibility for 802.11b devices using Orthogonal Frequency Division Multiplexing (OFDM) modulation technology.

Cisco has developed an access point that permits 802.11b and 802.11a devices to coexist on the same WLAN. The access point supplies ‘gateway’ services allowing these otherwise incompatible devices to communicate.

Miscellaneous Topics

MAC addresses

48bits = 12 hex digits

Peer-to-Peer network: Maximum of 10 hosts

URL

Example: http://www.slctech.org/work

http:// – protocol to use

www – type of site (ftp, www, etc)

slctech.org – domain name of the web site

/work – identifies the folder where the web page is located

DNS

.us United States

.ca Canada

.edu education

.com commercial

.gov government

.org non-profit

.net network service

.mil military

.int international database

DNS is used to translate a web addresses into their corresponding IP addresses

7.1.2 10BASE5

no more than 5 segments separated by more than 4 repeaters, and no more than three populated segments

8.2.2 Collision domains

7.1.9 Fast Ethernet architecture

7.1.9 Fast Ethernet architecture

802.2

7.1.1 10-Mbps and 100-Mbps Ethernet

8.2.3 Segmentation

9.1.6 Comparing the OSI model and the TCP/IP model