slides13

Question 1

IP layer options

Answer 1

• Security
• Record Route.
• Timestamp.
• Strict Source Routing.
• Loose Source Routing.

Question 2

why are IP addresses not random

Answer 2

If there were no structure on the addresses every router everywhere would have to know where every host in the world was

Question 3

how does a host decide between destination machine or gateway

Answer 3

It can tell if the destination is on the same network as itself by comparing the network part of their addresses

Question 4

how does a router decide in which direction to send the packets

Answer 4

A router contains a table of IP addresses, with next-hop routers associated with those addresses

Question 5

what does the router do with a packet and his table

Answer 5

• If the packet destination matches a host address in the table, send the packet to the indicated host on the indicated interface
• Else if the packet destination’s network part matches a network address in the table, send the packet to the indicated router on the indicated interface
• Else find an entry in the table marked “default”, and send the packet to the indicated router on the indicated interface
• Else error

Question 6

what is netmask

Answer 6

subdivision of IP that allows the router understand if something belongs to the same subnet as something else (divided into classes)

Question 7

what are classes

Answer 7

class A B C D E, leading 0, 10, 110, 1110, 1111