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GATE 2026 CS2 Q.22: solution and answer

GATE 2026 · CS2Q.22 · 1 mark · MCQ

Which one of the following protocols may need to broadcast some of its messages?

  1. (A)

    SMTP

  2. (B)

    FTP

  3. (C)

    DHCP

  4. (D)

    HTTP

See the question in the paper
GATE 2026 CS2 question 22Tap to open full size

Answer and solution

ANSWER

The answer is (C) DHCP.

Official answer: CSource: Official answer key, GATE 2026 CS2 (IIT Guwahati)

  1. SMTP, FTP and HTTP run over TCP. TCP is connection-oriented and point-to-point, so each of their messages goes to one known unicast address; none of them needs to be broadcast.

  2. DHCP runs over UDP, which can carry broadcast datagrams. A client that is booting has no IP address of its own and does not know any DHCP server's address.

  3. So the client sends DHCPDISCOVER with source 0.0.0.0 and destination 255.255.255.255 (the limited broadcast address), so that any DHCP server on the local network can receive it.

  4. The server's DHCPOFFER and DHCPACK may also be broadcast, because the client cannot yet receive unicast packets addressed to an IP address it does not hold.

  5. DHCP is therefore the only listed protocol that may need to broadcast some of its messages. The answer is (C).

KEY IDEA

Broadcast needs a connectionless transport (UDP) and a sender that does not yet know its peer's address. Only DHCP fits, because a booting host has no IP address and must discover a server by broadcast.

WATCH OUT FOR

Thinking that any application protocol can broadcast. SMTP, FTP and HTTP use TCP connections between two known hosts, so broadcast is impossible for them.

From the GATE 2026 CS2 paper. Every question of this paper · Download the full paper · All 20 IPv4 questions, with notes

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