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Q18.10 - In classless adressing, we know the first and the last...

If the first and the last addresses are known, the block is fully defined. We can first find

the number of addresses in the block (N) and the find the prefix length (n)

N (last address) - (first address) ! "

n #$ - log$N

%lock& (first address)'n

P18.8 - in classless addressing, what is the alue..

tep " of #

*he prefix can be found as n #$ - log$N&

a. n #$ - log$ " #$

b. n #$ - log$ "+$ $$

c. n #$ - log$$#$ +

Q19.12 - What are the source and destination I addresses in a datagram...

*he source I address is the I address of the router interface from which the original I

datagram is receied. *he destination I address is the I address of the original source

host that sent the original datagram. In other words, the reporting router in this case acts

as a source host. *his proes that a router needs an I address for each of itsinterfaces.

P19.6 - Which fields of the I...

*he following fields can be changed from one router to another&

a. /0N& if there is option change

b. *otal length& If fragmented or options change

c. 1lags& If fragmented

d. 1ragmentation 2ffset& If fragmented

e. *ime-to-/ie& decremented at each router

f. eader 3hecksum& Need to change because of other changes

Q20.12 - In a ery small 4s using 21...

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If the 4 is small, it is normally recommended to consider ir as only one area (the

backbone area) to reduce the oerhead of information exchange between areas.

Q23.6 - In a network, the si5e of the send windows...

We check each protocol one by one&

a. *he protocol cannot be the tp-and-Wait because the si5e of the send window should

be "

b. *he protocol can be 6o-%ack-N with the send window si5e of $+ and the receie

 window si5e of " packet

c. *he protocol can be electie-7epeat with the send window si5e of $+ and the receie

 window si5e of "+

P23.24- In a network using the electie87epeat...

*he following shoes the situation

a. *he sender has sent packets 9$ to 99: the receier is expecting only packet 9 in this

set (packets 9$ and 9# hae already been receied nd acknowledged). *his means

there is only one pending packet, packet 9.

b. *he receier has sent 43;s 9$, 9#, 9< and 99, but the sender has receied only 43k

9<. *his means 43;s 9$, 9# ans 99 are pending.

Q24.6 - 3an you explain why we...

*here are two parties inoled in a two-way communication. *3 allows each party to

stop sending while the other party is still sending data. *his means we need at least two

1IN segments (or data segments in which the 1IN bit is set). ince each 1IN segment

should be acknowledged, we normally need four segments for connection termination.

ometimes the second 1IN segment can be combined with the 43; segment to reduce

the number of segments to three.

P24.14 - *3p is sending data at " megabyte per second..

*he largest number in the se=uence number field is $>? - ". If we start as @+++, it takes

A($>?-")-@+++B'".+++.+++ $C< seconds.

Q25.8 - 4 source socket address..

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*he I address identifies the source computer: the port number identifies the source

process.