Suppose the propagation delay from your laptop to the local DNS server (and vice versa) is 1 ms. What is the minimal time it takes for your laptop to receive a DNS response for the DNS query it has just issued to the local DNS server? [For this and the following questions, you can assume that the transmission or other delays are negligible (i. e., zero!).] Briefly justify your answer.

The answer to the given question is described in the explanation section below.

Explanation:

DNS translates its titles to the IP addresses, allowing users to access Web resources.

As the latency of propagation is 1 millisecond from both the ends.

Let all the time needed for propagation from the laptop to DNS = 1 ms

Let the outcome time spent propagating through DNS to laptop = 1 ms

If all other broadcasts and pauses = 0 ms

Assume that 'n' DNS providers are accessed until the host collects DNS 'IP address; consecutive passes are sustained by RTT1,..., RTTn.

When IP address is identified, now let us say that RTT0 is needed to set up the TCP link and that the other RTT0 runs out to demand and collect the tiny entity to be made on a screen.

So total time will be,

=  1 + 1 + RTT0 + RTT0 + RTT1 + RTT2 + + RTTn

=  2 + 2(RTT0) + RTT1 + RTT2 + + RTTn