GATE | GATE-CS-2007 | Question 20

Which one of the following uses UDP as the transport protocol?
(A) HTTP
(B) Telnet
(C) DNS
(D) SMTP

Answer: (C)
Explanation: UDP is a stateless ,connectionless and unreliable protocol.
HTTP needs connection to be established and thus, uses TCP.
Telnet is a byte stream protocol which again needs connection establishment ,thus uses TCP.
DNS needs request and response ,it needs a protocol in which a server can answer the small queries of large number of users. As UDP is fast and stateless it is the most suitable protocol and thus, it is used in DNS querying .
SMTP needs reliability and thus, uses TCP.
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