Which of the following services use TCP?i) DHCP ii) SMTP iii) HTTP iv) TFTP v)…
2013
Which of the following services use TCP?
i) DHCP
ii) SMTP
iii) HTTP
iv) TFTP
v) FTP
- A.
i) and ii)
- B.
ii), iii) and v)
- C.
i), ii) and iv)
- D.
i), iii) and iv)
Attempted by 7 students.
Show answer & explanation
Correct answer: B
Concept — The transport protocol a service uses depends on what the application needs. TCP is connection-oriented and reliable: it performs a handshake and uses sequence numbers, acknowledgements and retransmission so that every byte arrives correctly and in order. UDP is connectionless and lightweight: it has no handshake and no built-in reliability, which suits bootstrapping, broadcast, or small low-overhead transfers.
Application — Classify each service by the transport it relies on:
SMTP uses TCP: an email message must arrive complete and in order.
HTTP uses TCP: a web page and its resources must be delivered reliably.
FTP uses TCP for both its control and data connections, so whole files transfer without loss.
DHCP uses UDP: a client broadcasts to obtain configuration before it even has an IP address, which fits connectionless UDP.
TFTP uses UDP: it is deliberately 'trivial' and carries its own minimal acknowledgement scheme on top of UDP instead of relying on TCP.
Cross-check — Collecting the TCP services gives SMTP, HTTP and FTP, that is items ii, iii and v.