Question \# 4:(7 Marks) (ILO A1, Outcome 1) A. (7 Marks) Consider the following scenario, a client wants to retrieve the www.microsoft.com page but the www.microsoft.com web server IP address is unknown. All links have 100Mbps capacity. Ignore queuing delay at the routers, and the packet processing delays at routers and nodes. a. Describe the process of the client obtaining the IP address for the hostname www.microsoft.com under the assumption that it is not cached at the local DNS server BUT that the DNS root server has cached an entry for the microsoft.com DNS server. The local DNS server also does NOT have cached the IP address of the .com TLD DNS. (Describe this for the iterated case!) b. After that first client, a second client connects to the same network as the first client and also wants to obtain the IP address for www.microsoft.com. Describe the process of the client obtaining the IP address in this case. c. Assume that the round trip time between local DNS server and DNS root server is 4RTT, between local DNS server and authoritative DNS server is 3RTT, and between the clients and the local DNS server is 2RTT. How long does it take for the first client to obtain the IP address for www.microsoft.com? d. The Microsoft main page is 500Kbits in size and refers to 9 additional web object (e.g., images) that all also have a size of 1500Kbits. Assume that the round trip time between client and server is 3RTT. Assuming non-persistent HTTP with no parallel TCP connections, how long does it take to download all web objects to the client? e. How long will it take to download all objects in the case of persistent HTTP? f. We know that www.microsoft.com is a very popular web site and the many client requests cannot be handled by a single server but rather by a cluster of web servers (each having a different IP address). Describe the process that DNS offers for load balancing. g. Now let us assume that independent of the URL, 30% of the web requests that originate from the local network can be satisfied by the local cache and 70% of the requests are satisfied at the origin (in this specific case we assume they are all satisfied by www.microsoft.com). The bandwidth between client and cache is 100Mbps in this case. What is the total average delay with which web objects are served to clients in the local network