A desktop mail client must both hand new messages to the company server and download the messages already waiting in the user's server-side mailbox. Which TWO of the following protocols are used for the download direction rather than for submitting or relaying mail?
LPIC-1 Exam 102-500, objective 108. Essential system services easy
Machine-checked — no person has signed for it. This question was read against the source cited below by an automated pass, which found no contradiction. That is a weaker claim than it sounds: the same kind of process wrote the question, so it can confirm its own mistake.
Treat it as a good draft rather than as settled fact, and read the source below before you rely on it. It is not used in mock exams here — only questions a person has signed for are.
How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
The options
Choose 2.
Not correct SMTP, port 25
Wrong direction. SMTP carries mail from a client or MTA towards the destination MTA; port 25 is the MTA-to-MTA relay port. It never fetches messages out of a mailbox.
Correct POP3, port 110
Correct. The Post Office Protocol downloads messages from the server mailbox to the client, classically deleting the server copy afterwards.
Correct IMAP, port 143
Correct. The Internet Message Access Protocol also retrieves mail, but keeps the authoritative copy and the folder structure on the server so several clients see the same state.
Not correct SMTP submission, port 587
Wrong direction. Port 587 is the dedicated submission port on which an MUA hands outgoing mail to its own MTA, normally with authentication required.
Not correct LDAP, port 389
Wrong. LDAP is a directory access protocol. Mail systems often use it to look up addresses or authenticate users, but it carries no messages.
Why
Mail moves in two distinct legs. Submission and relay are SMTP, on port 25 between MTAs and on port 587 from an MUA to its own MTA; retrieval from a mailbox is POP3 or IMAP and is a job of the MUA, not of the MTA. This is why installing an MTA alone gives a host the ability to send and to accept mail, but not the ability for remote clients to read it.
Where this comes from
- Cited
- manual page services(5)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 108 and space the ones you get wrong.
More questions on this objective
- You corrected the running system's clock with `date -s`, but after the next power cycle the machine came back with the old wrong time. Which command copies the corrected system clock into the hardware (RTC) clock? machine-checked
- On a systemd-based distribution, which file determines the local time zone used by the C library when formatting times? machine-checked
- A host runs chrony as its NTP client. Which command shows the list of time sources chrony is currently talking to and how it rates each one? machine-checked
- In /etc/ntp.conf you find the line `server 0.pool.ntp.org iburst`. What does the `iburst` keyword do? machine-checked
- A minimal systemd host synchronises its clock with systemd-timesyncd. Which statement about that service is accurate? machine-checked
- On a systemd host, type the single command that turns on automatic network time synchronisation (do not include a path). machine-checked