Suppose DNS is implemented on top of TCP instead of UDP. Assume TCP

will be used in all DNS queries and answers between all DNS servers $($and between your

phone and the local DNS server$).$ Also, note that the minimal time to send a request $($in a

single data packet$)$ from a client to a server and gets a response from the server will take

at least $2$ RTTs $($round$-$trip$-$times$).$