A remote site was unreachable for an hour and messages for it accumulated in the local queue. The link is now restored and you do not want to wait for the next scheduled queue run. Which sendmail-emulation command asks the MTA to attempt delivery of the queued messages immediately?
LPIC-1 Exam 102-500, objective 108. Essential system services hard
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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 sendmail -q
Correct. -q with no interval argument processes the queue once, straight away, attempting delivery of every message currently held.
Not correct sendmail -bp
Wrong. -bp only prints the queue and its deferred reasons. It is a report; it triggers no delivery attempt.
Not correct sendmail -bd
Wrong, and disruptive. -bd starts the MTA as a background daemon listening for incoming SMTP connections. On a host where the MTA is already running this either fails on the bound port or starts a second instance.
Not correct sendmail -bi
Wrong. -bi rebuilds the alias database from the alias source file, which is what newaliases does. It has no effect on messages already queued.
Why
Deferred messages stay in the queue and are retried on a schedule that widens over time, so a manual queue run is the way to flush them after a fault is fixed. Distinguish the mode options: -q runs the queue, -bp reports it, -bd starts the daemon and -bi initialises aliases; written as -q30m the option instead sets a repeating interval. Postfix administrators can reach the same effect natively with postqueue -f, and Exim with exim -q.
Where this comes from
- Cited
- manual page sendmail(1)
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.
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