CompTIA A+ Core 1 (220-1201)NetworkingHard
A user's email client is configured to download and remove messages from the mail server onto a single device, while a colleague's client is configured to leave copies of messages on the server so multiple devices stay synchronized. Which two protocols and their default ports correspond to these two mail retrieval behaviors, respectively?
- ASMTP on TCP 25; POP3 on TCP 110
- BIMAP on TCP 143; POP3 on TCP 110
- CPOP3 on TCP 995; IMAP on TCP 993
- DPOP3 on TCP 110; IMAP on TCP 143
Show answer & explanationAnswer & explanation
Correct answer: D. POP3 on TCP 110; IMAP on TCP 143
POP3 (TCP 110) traditionally downloads mail to a single device and removes it from the server, while IMAP (TCP 143) keeps mail synchronized on the server so it can be accessed from multiple devices. The scenario describes exactly these two behaviors in that order.
Why the other options are wrong
- A. SMTP is used for sending mail, not retrieval, so it doesn't match either behavior described.
- B. This reverses the correct protocol-to-behavior mapping.
- C. 995 and 993 are the encrypted (SSL/TLS) versions of these ports, not the default unencrypted ports referenced in the scenario.
POP3 vs IMAP
POP3 (TCP 110) downloads and typically removes email from the server for single-device access; IMAP (TCP 143) keeps messages on the server for synchronized multi-device access.
- POP3 default port is 110; secure POP3 uses 995
- IMAP default port is 143; secure IMAP uses 993
- IMAP is preferred when accessing mail from multiple devices
Memory trick: POP pulls and pops it off the server; IMAP keeps it in mutual access.