LPIC-1 Administrative Tasks Practice Question
A small business uses a Linux server running CUPS to share a network printer. For several months, all employees could print successfully. Today, an employee in a different subnet reports that printing does not work. The administrator checks the server: cupsd is running, the printer is configured with an IPP URI pointing to the printer's IP address, and the printer is idle. The administrator can ping the printer from the server. The administrator checks the CUPS error log and sees the following line multiple times: 'E [04/Oct/2024:10:15:22 -0400] [Client 5] client-error-not-authorized'. Which of the following actions should the administrator take to resolve the issue?
⚠ Common exam trap
Watch out — candidates often confuse 'client-error-not-authorized' with authentication issues (e.g., missing username/password) or service problems, when it is actually an IP-based access control restriction in CUPS' policy configuration.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add 'Allow from 192.168.2.0/24' to the appropriate policy in /etc/cups/cupsd.conf
The error 'client-error-not-authorized' in CUPS indicates that the client's request was denied due to access control restrictions in cupsd.conf. Since the employee is in a different subnet (e.g., 192.168.2.0/24), the default CUPS policy likely only allows local subnet access. Adding 'Allow from 192.168.2.0/24' to the appropriate policy (e.g., under <Policy default>) grants printing access from that subnet, resolving the authorization failure.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Change the printer's URI from ipp:// to socket://
Why it's wrong here
Switching to socket:// bypasses IPP authentication entirely, but the error is an authorisation rejection, not a protocol or transport failure — the printer is reachable and idle. socket:// suits legacy printers lacking IPP support, where raw port 9100 printing is the only available method. Here it would discard IPP without addressing the CUPS access policy denying the client.
- ✗
Add the employee's username to the lpadmin group
Why it's wrong here
Adding the user to lpadmin grants printer administration rights, not print-job submission, so it cannot clear a client-error-not-authorized on a job. It is tempting because lpadmin membership does control CUPS administrative access, and would be the right fix if the employee needed to add or modify printers via the web interface.
- ✗
Restart the cupsd service with 'systemctl restart cupsd'
Why it's wrong here
Restarting cupsd clears no authorisation state: the `client-error-not-authorized` line shows CUPS rejecting the client under its access controls, and a restart reloads the same configuration. It is tempting because restarting is the standard first step after configuration edits, and would be right if cupsd had crashed or were ignoring a newly added printer.
- ✓
Add 'Allow from 192.168.2.0/24' to the appropriate policy in /etc/cups/cupsd.conf
Why this is correct
The error 'client-error-not-authorized' shows CUPS is rejecting the client's IP via its access control policy. Since the employee sits in a different subnet, adding an Allow directive for 192.168.2.0/24 to the relevant Location or policy block in cupsd.conf restores authorisation.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This LPIC-1 practice question is part of Courseiva's free LPI certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LPIC-1 exam.