Essential system services
Essential system services covers the system clock and NTP, system logging with rsyslog and the systemd journal, mail transfer agent basics, and CUPS printing. Objective 108 of LPIC-1 Exam 102-500, worth 18.33% of the exam.
- Share of the exam
- 18.33%
- Questions in a real sitting
- roughly 11 of 60
- Questions in this bank
- 60
- Signed for by a person
- 0
- Machine-checked only
- 60
Partly checked. None of the 60 questions here has been read against the cited source by a person. 60 questions have been checked against their cited clause by an automated pass — which is not the same thing, and is not a signature.
Only questions a person has signed for are used in mock exams here. That is the whole difference between the two kinds of checking above.
How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
What this objective covers
The 60 questions written for this objective cite 4 LPI exam objectives (108.1, 108.2, 108.3, 108.4) and 26 manual pages (adjtime(5), aliases(5), cancel(1), chrony.conf(5), cupsd.conf(5), date(1), hier(7), hwclock(8), journalctl(1), journald.conf(5), local(8), logrotate(8), lp(1), lpadmin(8), lpmove(8), lpstat(1), mailx(1), ntpdate(8), ntpq(8), postfix(1), rsyslog.conf(5), sendmail(1), services(5), systemd-cat(1), timedatectl(1), tzfile(5)).
They break down as 41 single-answer questions, 10 type-the-answer questions and 9 choose-several questions.
What this objective is really about
Four services that every machine runs and that an administrator is expected to be able to inspect and adjust. The depth required is shallow but the breadth is real, so the risk is not difficulty but simply not having seen a tool before.
Time
Linux keeps two clocks: the system clock the kernel maintains, and the battery-backed hardware clock. date reads and writes only the system clock, which is why a correction made with date alone is lost at the next power cycle. hwclock bridges them — --systohc (or -w) writes system to hardware, --hctosys (or -s) pulls the other way.
For synchronisation, chrony is queried with chronyc: sources for the source list, tracking for the local clock's offset. The classic ntpd equivalent is ntpq -p. The iburst keyword on a server line sends a short burst of packets while the source is unreachable, which cuts the time to first sync dramatically. systemd-timesyncd is a client-only SNTP implementation — it can set the local clock but cannot serve time to others, and timedatectl set-ntp true is what turns synchronisation on.
Logging
A syslog selector is facility.severity. The eight severities, most to least urgent, are emerg, alert, crit, err, warning, notice, info, debug — and a bare severity in a selector matches that level and everything more urgent. rsyslog adds modifiers: = for exactly one level, and none for suppressing a facility inside a multi-selector line. Facilities are a fixed list; local0 through local7 are deliberately left undefined for local use, which is what logger -p local3.info exists to exploit.
The journal is a structured binary store queried with journalctl, not a text file you can grep. The filters worth memorising: -u for one unit, -f to follow, -b for the current boot and -b -1 for the previous one, -p for a severity and above, -k for kernel messages. Boot offsets only work if the journal is persistent, which means /var/log/journal exists or Storage=persistent is set — with the default, the journal lives in a tmpfs and is lost at every reboot.
On most distributions journald and rsyslog coexist: journald receives everything and rsyslog consumes from it to produce the familiar text files. Log rotation is a separate concern again, handled by logrotate running periodically, with global defaults in /etc/logrotate.conf and per-package snippets in /etc/logrotate.d.
Mail and printing
Mail forwarding splits by authority. Root edits /etc/aliases and then runs newaliases, because the MTA reads a compiled database rather than the text file — forgetting that rebuild is why a correct-looking alias bounces. Any user can create ~/.forward in their own home directory without administrator involvement. mailq lists the outbound queue on every common MTA. Know the roles apart: an MTA (postfix, exim, sendmail, qmail) moves mail between hosts, an MDA (procmail) files an accepted message, and fetchmail pulls mail down from a remote server.
CUPS ships both the Berkeley tools (lpr, lpq, lprm) and the System V ones (lp, lpstat, cancel) over the same queues. It has two independent per-destination switches that questions like to conflate: cupsaccept and cupsreject control whether new jobs are accepted, while cupsenable and cupsdisable control whether queued jobs are printed. Taking a printer down cleanly usually means rejecting first so nothing accumulates. The daemon listens on port 631 and its configuration lives in /etc/cups.
Lessons in this objective
The objective cut into the pieces the blueprint declares. Each one has the material written out and the questions that test it.
Drill this objective
The trainer can run a short practice set drawn from this objective alone, which is what the weight column above is for: revise the heavy objectives first.
Practise Essential system services
Questions on this objective (page 1 of 3)
- 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
- You have just set the system clock correctly by hand and want the hardware clock to match, so the correction survives a reboot. Type the command, using its short option. machine-checked
- An rsyslog rule reads `mail.warning /var/log/mail-problems`. Which messages from the mail facility does this rule write to that file? machine-checked
- Which of the following are valid standard syslog facility names usable on the left-hand side of an rsyslog selector? (Choose three.) machine-checked
- A backup shell script must write its own status line into the system log through the syslog service. Type the name of the standard command-line utility it should call (command name only, no options). machine-checked
- Which statement correctly describes how logrotate is configured on a typical distribution? machine-checked
- You want to watch new log entries for the sshd service as they arrive, on a systemd host. Which command does exactly that? machine-checked
- A server crashed and has since rebooted. You want the journal entries of severity error and above from the boot before the current one. Which command retrieves them? machine-checked
- On a host where journalctl shows nothing from before the last reboot, which change makes the journal persist across reboots? machine-checked
- On a distribution that runs both systemd-journald and rsyslog, which two statements are correct? (Choose two.) machine-checked
- You added the line `helpdesk: alice, bob` to /etc/aliases, but mail to helpdesk still bounces. What is the most likely reason? machine-checked
- An ordinary user with no administrative rights wants all mail delivered to their account forwarded to an external address. Which mechanism is intended for that? machine-checked
- Type the traditional command, present on Sendmail, Postfix and Exim alike, that lists the messages currently waiting in the local mail queue. machine-checked
- Which of the following are mail transfer agents, that is, programs whose job is to accept and relay mail between systems using SMTP? (Choose three.) machine-checked
- A print job you submitted is stuck and you want to remove it from the CUPS queue. Which pair of commands finds the job id and then deletes that job? machine-checked
Practise Essential system services
The other objectives in LPIC-1 Exam 102-500
- 105. Shells and shell scripting — 15% of the exam
- 106. User interfaces and desktops — 6.67% of the exam
- 107. Administrative tasks — 20% of the exam
- 109. Networking fundamentals — 23.33% of the exam
- 110. Security — 16.67% of the exam