LPIC-1 Essential System Services and Networking Practice Question
A Linux server running multiple virtual hosts on Apache suddenly becomes unresponsive to web requests. The administrator finds that the server still responds to ping. Which diagnostic command would best identify whether Apache is accepting connections?
⚠ Common exam trap
A common mix-up: candidates choose `curl -I http://localhost` thinking it tests Apache directly, but it actually tests the full HTTP request/response cycle, which can fail for reasons unrelated to Apache's listening state (e.g., firewall, SELinux, or virtual host misconfiguration), whereas `ss` directly inspects the TCP listener without relying on higher-layer protocols.
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
✓
ss -tlnp | grep :80
`ss -tlnp | grep :80` lists all TCP sockets that are listening (`-l`), numeric (`-n`), and shows the process using the socket (`-p`). Filtering for port 80 directly reveals whether Apache's httpd process is actively listening for incoming connections, which is the most direct way to confirm that Apache is accepting connections at the transport layer.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
ip route show
Why it's wrong here
Shows routing table, not service listening.
- ✗
curl -I http://localhost
Why it's wrong here
Tests HTTP response, but if Apache is not listening, curl will hang; better to first check listening.
- ✗
ping -c 4 localhost
Why it's wrong here
Tests local ICMP, not HTTP service.
- ✓
ss -tlnp | grep :80
Why this is correct
Shows if Apache is listening on port 80.
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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.