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Within an organization NAT router NR$1$ is connected to LAN through interface etho and a private IP $0\mathrm{.}10\mathrm{.}10\mathrm{.}0/24$ is assigned to this interface. NR$1$ is connected to Internet through interface ethl and a public $8.110\mathrm{.}5\mathrm{.}5\mathrm{.}5/28$ is assigned to this interface. Two PCs of the LAN PC$1$ and PC$2$ have IP addresses $10\mathrm{.}10.\frac{10\mathrm{.}5}{24}$ and $10\mathrm{.}10\mathrm{.}10\mathrm{.}6/24$ respectively. Yahoo web server IP address is $100\mathrm{.}8\mathrm{.}8\mathrm{.}8/20.$ Trace the to and fro movernen? of packets Pland P$2$ from PC$1$ and of packet P$3$ from PC$2$ to yahoo web server. Show the entries of NAT table at NRI form for these packets.

$($b$)$ How traceroute works? How it is decided that the trace is complete?

$($c$)$ While sending HTTP request, the TCP SYN message and the HTTP GET message will be directed to the same socket at the server. Comment with reasons on the truthfulness of this statement.

$($d$)$ Typically web caches $($proxy servers$)$ are installed by organizations to reduce the response time of clictit requests. How this is achieved? How it is ensured that client does not get served an outdated HTML page from the cache?

$($c$)$ What is the purpose of the HTTP "COOKIE:" field? Are the values in the HITP mesage's cookie ficte stored at the client or server or both? Explain briefly.

$($O$)$ Taking an example network of your choiee, explain briefly the step by step working of RIP Which underlying layer protocol is used by RIP, OSPF and BGP$?$