You added the line `helpdesk: alice, bob` to /etc/aliases, but mail to helpdesk still bounces. What is the most likely reason?
LPIC-1 Exam 102-500, objective 108. Essential system services medium
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
Correct The alias file has not been rebuilt into the indexed database the MTA actually reads.
Correct. The MTA consults a compiled database (typically /etc/aliases.db), not the text file. Running `newaliases` regenerates it, after which the alias resolves.
Not correct Aliases only work for local users, and alice and bob must be listed by UID rather than by name.
Wrong. Alias targets are written as user names or full email addresses. UIDs are never used in /etc/aliases.
Not correct An alias may expand to only one recipient, so a comma-separated list is rejected.
Wrong. A comma-separated list of recipients is the normal way to write a distribution alias.
Not correct /etc/aliases is read only at boot, so the machine must be rebooted.
Wrong. No reboot is involved. The file is turned into the database on demand by newaliases, and the running MTA picks the new database up without restarting.
Why
/etc/aliases maps a local name to one or more destinations, which may be local users, remote addresses, a file, or a command via a pipe. The text file is only the source: `newaliases` (equivalent to `sendmail -bi`, and to `postalias /etc/aliases` under Postfix) compiles it into the indexed map the MTA queries at delivery time. A conventional entry every system should have is `root: someadmin`, so root's mail reaches a human.
Where this comes from
- Cited
- LPI exam objective 108.3
- What it says
- Create e-mail aliases and rebuild the alias database.
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
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