GATE CSE 2015 Set 1 | Question: 1‏7

Question

In one of the pairs of protocols given below , both the protocols can use multiple $\textsf{TCP}$ connections between the same client and the server. Which one is that?

• A. $\textsf{HTTP, FTP}$
• B. $\textsf{HTTP, TELNET}$
• C. $\textsf{FTP, SMTP}$
• D. $\textsf{HTTP, SMTP}$

Comments

@skyby, having TCP connection does not implies stateful connection.

for eg. HTTP uses TCP but a stateless protocol.

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HTTP uses multiple TCP connections. Based on this concept, a question has been asked in GATE 2020.

https://gateoverflow.in/333206/gate-2020-cse-question-25

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Shiva Sagar Rao

yes in case of non persistent connection!

Answer 1

$\textsf{SMTP:}$ only one $\textsf{TCP}$ connection.

• Reference: https://tools.ietf.org/html/rfc821

$\textsf{TELNET:}$ only one $\textsf{TCP}$ connection.

• Reference: https://tools.ietf.org/html/rfc854

$\textsf{HTTP:}$ Multiple connections can be used for each resource.

• Reference: http://www.w3.org/Protocols/rfc2616/rfc2616-sec1.html#sec1

$\textsf{FTP: FTP}$ uses Telnet protocol for Control info on a $\textsf{TCP}$ connection and another $\textsf{TCP}$ connection for data exchange

• Reference: https://tools.ietf.org/html/rfc959 $\text{(See page 8)}$

So, the answer is A. 

Comments

Rupendra Choudhary sir, even if you open two tabs of the same website in your browser, does that not establish two TCP connections between your machine's browser, and the corresponding website's server?

 

And regarding SMTP, it can send multiple messages from the same client to the same server, but it doesn't make multiple simultaneous TCP connections for it. Just one persistent TCP connection is enough.

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Multiple implies more than 1, then in FTP, can we have say 10 TCP connections between client and server?

If not FTP would not be the answer.

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@zeeshanmohnavi

thanks :)

JashanArora

so in http both persistent and non persistent connections possible and in SMTP only persistent connection possible?

Answer 2

Option A....most likely