Why Does Persistent HTTP Have an Extra RTT?

[perplexabot]

Hello all. I am trying to understand number 2c of this pdf:
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDEQFjAA&url=http%3A%2F%2Fwww.nyu.edu%2Fclasses%2Fjcf%2FCSCI-GA.2262-001_fa12%2Fhandouts%2FHomework2Solutions.pdf&ei=DX1sUurmCeOYiQKnwYFg&usg=AFQjCNElBG4mGrEvpyPHCu4HeWcWQYGxSA&sig2=0D9G34-MeX0IDDOVNdZWhQ&bvm=bv.55123115,d.cGE.

I have tried solving it on my own but I got the wrong answer. I am starting to get irritated.

How I solved the problem:
Time for DNS to supply client with IP: RTT1 + ... + RTTn
Time for client to have initial handshake: RTT0
Time for client to receive all message: RTT0

Total time = RTT1 + ... + RTTn + RTT0 + RTT0 = RTT1 + ... + RTTn + (2 * RTT0)

According to the answer I am missing a RTT0. I have no idea where that extra RTT0 comes from. May someone please help me out?

 

[perplexabot]

I think I realize why now. Is it because, first you have to request the base HTML file, and it is until this file is received at the client that the client can go on and ask about the objects contained in that HTML file? Hence, two different RTTs will occur.

Can someone confirm this?

 

[harborsparrow]

I think I realize why now. Is it because, first you have to request the base HTML file, and it is until this file is received at the client that the client can go on and ask about the objects contained in that HTML file? Hence, two different RTTs will occur.

Can someone confirm this?

Seems right to me.