IP Addressing

Question 1

InterNIC

Answer 1

Internet Network Information Center (international organization primarily responsible for the allocation of domain name and IP address)

Question 2

Normal Public masks Class A = Class B = Class C =

Answer 2

Class A = 255.0.0.0 Class B = 255.255.0.0 Class C = 255.255.255.0

Question 3

The /X

Answer 3

The /X = the number of 1’s in the binary mask. There are a total of 8 possible 1’s for each octet. 255 has 8 1’s, so 255.0.0.0 is a /8. 255.255.0.0 = /16 etc…

Question 4

Possible number of subnets

Answer 4

To find the number of subnets use 2^n for the on bits 172.20.0.0 255.255.255.224 11111111.11111111.11111111.11100000 (11 bits on) so 2^11=2048 subnets

Question 5

Possible Number of hosts per subnet

Answer 5

To find the number of host per subnet use 2^n-2 for the off bits

172.20.0.0 255.255.255.224 11111111.11111111.11111111.11100000 (5 bits off) so 2^5-2=30 host per subnet So a mask of 255.255.255.224 = 11111111.11111111.11111111.11100000 Each octet represents 128,64,32,16,8,4,2,1 or 2n where n is the position from the left. So the last “1” is in the 32 position and 256-224=32 you have to subtract the network and the broadcast address to get the number of hosts = 30.

Question 6

Most Significant bits (MSBs) ?

1. Class A =
2. Class B =
3. Class C =

Answer 6

Most Significant bits (MSBs)?

1. Class A = 0
2. Class B = 10
3. Class C = 110

Question 7

What command would you use to determine if all seven layers of OSI reference model are operational between a local and remote host and gain login access to the remote host

Answer 7

Telnet

Question 8

What are the 4 DHCP messages and are they Broadcast or Unicast

Answer 8

DHCPDISCOVER (Broadcast) Client to Server

DHCPOFFER (Unicast) Server to Client

DHCPREQUEST (Broadcast) Client to Server

DHCPACK or DHCPNAK (Unicast) Server to Client

Question 9

IOS interface configuration Command is used to enable DHCP relay agent on the specified router interface.

Answer 9

ip helper-address

Question 10

Protocol - What Protocol is used to obtain the IP address for a machine based on the MAC address.

Answer 10

RARP - Reverse Address Resolution Protocol

Question 11

NAT

Answer 11

NAT - 4 Types 1. Static 2. Dynamic - Maps a Private IP to a Public address from a range of Public IPs. (Translation table populated as the required traffic flows through the NAT enabled device) 3. Overloading 4. Overlapping

Question 12

IOS command will enable you to use hostnames with the Ping or traceroute commands in place of IPs

Answer 12

ip domain-lookup

Question 13

IOS command to specify the IP address of one or more DNS Servers

Answer 13

ip name-server

Question 14

DNS

Answer 14

Service responsible for resolving WEB URLs to their assigned IP and vise versa.

Question 15

IOS Command to re-enable DHCP and DHCP relay agent if disabled.

Answer 15

service dhcp

Question 16

Troubleshooting; 1. The 3 approaches for troubleshooting network problems using the OSI layered model are:

Answer 16

The 3 approaches for troubleshooting network problems using the OSI layered model are: a. Bottom Up b. Top Down c. Divide and Conquer (Use if interface and protocol up)

Question 17

SDM; Cisco Security Device Manager (SDM); Which window on SDM ver. 2.3.1 shows the configured dynamic NAT configuration?

Answer 17

Edit NAT Configuration Window

Question 18

DEVICE enables a host to acquire an IP address from a DHCP server on a different subnet.

Answer 18

DHCP relay agent

Question 19

IOS Command - Which allows you to change the packet load and other ICMP parameters to test the connectivity to a remote device.

Answer 19

extended ping

Question 20

IOS Command - Which will let you see the IP address configured on the interface of directly connected remote routers on a P2P WAN Link.

Answer 20

show cdp neighbor detail

Question 21

IOS interface configuration Command that will enable that interface to acquire an IP address from a DHCP server.

Answer 21

ip address dhcp

Question 22

What are the components of an IP address.

Answer 22

network ID

Host ID

Subnet ID

Question 23

Protocol used to resolve MAC address to IP address mappings.

Answer 23

ARP

Question 24

SDM; What are the two options available on SDM 2.3.1 utility to configure dynamic NAT.

Answer 24

Basic NAT Advanced NAT

Question 25

What factor determines the number of simultaneous translations that a router will support?

Answer 25

Amount of DRAM on the router.

Question 26

In situations where the same subnet mask must be used for multiple interfaces on a router, what principle should guide the selection of the mask

Answer 26

The mask must provide capacity sufficient for the largest number of hosts on a single interface while also providing the required number of subnets.

Question 27

To Find a Broadcast Address?

Answer 27

To Find a Broadcast Address, you must first find the network ID by adding the binary address with the mask. Then, use the number of subnet or host, to find the last ip in the range.

Question 28

ARP

Answer 28

IP address mapping to a MAC address

Question 29

RARP

Answer 29

MAC address of source IP address

Question 30

Write Out subnetting help table.

Answer 30

128 64 32 16 8 4 2 1

128

192

224

240

248

252

254

255

————— hosts (2^n) (subtract 2 to get rid of network ID and Broadcast IP)

2 n=1

4

8

16

32

64

128

256 n=8

512

1024

2048

4096 n=12

8192

16384

32768

65536 n=16

Question 31

If Default Subnet mask is use, the public Class A =

Answer 31

Class A - 1.0.0.0 to 127.0.0.0

Question 32

If Default Subnet mask is use, the public Class B =

Answer 32

Class B - 128.0.0.0 to 191.255.0.0

Question 33

If Default Subnet mask is use, the public Class C =

Answer 33

Class C - 192.0.0.0 to 223.255.255.0

Question 34

Private IP Class A address ranges:

Answer 34

10.0.0.0 Class A (255.0.0.0 or /8) through 10.255.255.255)

Question 35

Private (APIPA only) IP address ranges:

Answer 35

169.254.0.0 through 169.254.255.255 (APIPA only)

Question 36

Private IP Class B address ranges:

Answer 36

172.16.0.0 Class B (255.240.0.0 or /12) through 172.31.255.255 (16 contiguous class B network)

Question 37

Private IP Class C address ranges:

Answer 37

192.168.0.0 Class C (255.255.0.0 or /16) through 192.168.255.255 (256 contiguous class C network)

Question 38

Public IP addresses

Answer 38

IP address are classified into 3 class’s (groups) depending on the decimal equivalent of the 1st octet in the address as below:

0-255.xxx.xxx.xxx = all address’s

Class A

Intended for a small number of networks that had a large number of computers (hosts) attached. Class A IP Address have a value in the range 1…126 as the first octet. The values 0 and 127 are not available because they have special uses. Class A addresses use the first octet to identify the network which means that 126 addresses are usable, each of which can support 16,777,216 computers (hosts).

Class B

Intended for some networks that had an intermediate number of computers (hosts) attached. Class B IP Addresses have a value in the range 128…191 as the first octet. Class B addresses use the first two octets to identify the network which means that 16,320 addresses are usable, each of which can support 65,536 computers (hosts).

Class C

Intended for a large number of networks that would have a small (relatively) number of computers (hosts) attached. Class C IP Addresses have a value in the range 192…223 as the first octet. Class C addresses use the first three octets to identify the network which means that 2,080,800 addresses (networks) are possible, each of which can support 254 computers (hosts).