IP

Question 1

True/False - A device on one subnet cannot communicate with another device on a different subnet without the help of a router

Answer 1

True

Question 2

True/False - Subnetting is transparent to the rest of the internet

Answer 2

True

Question 3

Define subnetting

Answer 3

The process of dividing a network into smaller sized networks

Question 4

How many hosts are possible on a Class B network

Answer 4

( 2 ^ 16 ) - 2

Question 5

How many hosts are possible on a Class A network

Answer 5

(2 ^ 24 ) - 2

Question 6

How many hosts are possible on a Class C network

Answer 6

( 2 ^ 8 ) - 2

Question 7

What is the purpose of the special IP address 0.0.0.0

Answer 7

Only used in a local network for a src ip until DHCP gives an IP

Question 8

What is the purpose of the special IP address 255.255.255.255

Answer 8

Limited Broadcast - only for a dst ip in a local network

Question 9

What are the characteristics of the special IP address type, Network Address

Answer 9

Host ID is all 0’s, cant be used to address to a device

Question 10

What are the characteristics of the special IP address type, Direct Broadcast

Answer 10

Net ID is specified, host portion is all 1’s, allows broadcast to a different network

Question 11

How would a special IP address for a specific host on a network look

Answer 11

network id is all 0’s, host id is specified

Question 12

What is the loopback address and what is its purpose

Answer 12

127.x.x.x , doesnt leave local interface

Question 13

What are the private IP ranges

Answer 13

10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168. 0. 0 - 192.168.255.255

Question 14

Describe a subnet mask in terms of the 32 bit sequence

Answer 14

A 32 bit sequence that contains a 1 in every network/subnet portion bit and a 0 in every host portion bit

Question 15

True/False - All devices including hosts and routers that are located on the same network/subnet must have the same subnet mask

Answer 15

True

Question 16

True/False - Devices on different subnets may have the same subnet mask

Answer 16

True

Question 17

True/False - To find the network address, take the IP address and BIT AND it with the subnet mask

Answer 17

True

Question 18

True/False - IP is a connectionless, unreliable, best-effort service

Answer 18

True

Question 19

True/False - Routers in the internet ignore the protocol field

Answer 19

True

Question 20

True/False - IP just checks the header for errors, not the payload

Answer 20

True

Question 21

True/False - To get the size of the payload take the Total Len and subtract the Hdr Len

Answer 21

True

Question 22

True/False - Maximum Transmission Unit (MTU) is the Largest Payload a frame can handle

Answer 22

True

Question 23

True/False - Internet routers treat each fragment as an independent packet

Answer 23

True

Question 24

True/False - The last fragment must be a multple of 8

Answer 24

False

Question 25

True/False - Both end-systems and any internet router can fragment a packet

Answer 25

True

Question 26

True/False - if the rx’er doesnt get all the set of fragments it will drop all the the fragments

Answer 26

True

Question 27

True/False - All devices including hosts and routers that are attached to the same network must have the same network id portion

Answer 27

True

Question 28

Describe the NAT/PAT process

Answer 28

• The host creates a packet with its private src IP and its dst IP
• The host creates a frame with its src MAC and dst MAC of local router
• The local router processes the frame and looks at the packet, it sees a private IP as src and replaces the private src ip with the routers public ip
• The local router gets the src port from the payload and maps it to a selected different port in the NAT table. It changes the src port in the payload
• The local router puts an entry in the NAT table with the private IP of the sending host
• When the response comes back the local router finds the port mapping in the nat table to find out which devices to send to
• the local router replaces the dst IP with the original hosts private src IP

Question 29

True/False - Home routers have higher layer functions, internet routers are strictly layer 3

Answer 29

True

Question 30

What are the characteristics of a Class A Network

Answer 30

0-127, First bit 0, Net ID: 7 bits (2^7 Networks), Host ID: 24 bits (2^24 Hosts)

Question 31

What are the characteristics of a Class B Network

Answer 31

128-191, First bits 10, Net ID: 14 bits (2^14 Networks), Host ID: 16 bits (2^16 Hosts)

Question 32

What are the characteristics of a Class C Network

Answer 32

192-223, First bits 110, Net ID: 21 bits (2^21 Networks), Host ID: 8 bits (2^8 hosts)

Question 33

True/False - When you BIT AND your own IP with your own subnet mask you get your own network ID

Answer 33

True

Question 34

True/False - When you BIT AND another host IP with your own subnet mask you get the other host network ID

Answer 34

False

Question 35

True/False - /31 can represent a point-to-point link

Answer 35

True

Question 36

What is the block format

Answer 36

a.b.c.d/n

Question 37

What is the size of a block

Answer 37

The number of ip addresses in the block, 2^32-n

Question 38

What is the number of addressable devices in a block

Answer 38

2^32-n - 2

Question 39

True/False - In the case of multiple matches in the routing table the router will choose the longest prefix match

Answer 39

True

Question 40

What is the DV (Bellman-Ford) Formula

Answer 40

Dx(y) = min{c(x,v) +dv(y)}