Network protocols
OCR GCSE Computer Science revision on Network protocols. Aligned to the OCR GCSE Computer Science J277 specification. This bank has 8 practice questions on this topic.
Sample questions (3 of 8)
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Question 1
HTTPS uses port number...
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Answer: 443
Common ports to memorise for the exam: HTTP=80, HTTPS=443, FTP=20/21, SMTP=25, IMAP=143, POP3=110, SSH=22, DNS=53. HTTPS adds encryption (TLS) on top of HTTP — the 'S' stands for 'Secure'. Port numbers identify which service handles incoming packets at an IP address.
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Question 2
Which protocol is used to send emails between mail servers?
- A) IMAP
- B) SMTP
- C) POP3
- D) HTTP
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Answer: SMTP
SMTP — sends mail (server-to-server, and your email client to your provider's outgoing server). IMAP — fetches mail leaving it on the server, syncs across devices. POP3 — fetches mail and (usually) deletes from the server. So if you can't send email, SMTP is misconfigured; can't receive, IMAP/POP3.
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Question 3
The TCP/IP model has how many layers?
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Answer: 4
TCP/IP layers (bottom up): Link (Ethernet, Wi-Fi), Internet (IP, ICMP), Transport (TCP, UDP), Application (HTTP, SMTP, DNS). The OSI model splits these further into 7 layers — more theoretical, used in teaching. Each layer only talks to layers directly above + below it (encapsulation).
Want to test yourself on the remaining cards for this topic?
5 more questions on Network protocols — plus mistakes tracking and spaced repetition across the whole Computer Science spec.