GATE CS Mastery
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GATE CS 2015 Set 1 · Computer Networks

Question 27

MCQPrinted as CS Q.171 markWrong answer: −1/3Easy (estimate)

Question

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

Choose one option
Official answer and solution
Official answer
A
From
Official GATE 2015 answer key

Solution

Analyze the connection architecture of application-layer protocols over TCP.

  1. FTP (File Transfer Protocol):
    FTP inherently uses two separate TCP connections simultaneously between the client and server:

    • A Control Connection on port 21 for commands and responses.
    • One or more Data Connections (typically port 20 in active mode or ephemeral ports in passive mode) opened per file transfer or directory listing.

  2. HTTP (Hypertext Transfer Protocol):

    • In HTTP/1.0 and HTTP/1.1, web browsers typically open multiple parallel TCP connections (traditionally 4 to 8 concurrent sockets) to the same origin server to download embedded web resources (images, stylesheets, scripts) simultaneously.

  3. Other protocols:

    • TELNET and SMTP operate over a single persistent TCP connection between client and server for a given session.

Thus, both HTTP and FTP can use multiple TCP connections between the same client and server (option A).

Final answer

A

Common trap

Assuming HTTP only uses a single TCP connection, overlooking parallel TCP connection behavior in standard browsers.

The answer is the one in the official GATE answer key. The solution is this site's own explanation.

Source

Paper
GATE 2015 Computer Science and Information Technology (CS) Session 1
Question
27 of 65, printed as CS Q.17
Section
Computer Science and Information Technology

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