LPIC-1 Essential System Services and Networking Practice Question
An administrator is troubleshooting a DNS issue. The command 'dig @8.8.8.8 example.com' returns a response, but 'host example.com' returns 'Host not found'. Which of the following is the most likely cause?
⚠ Common exam trap
The trap here is that candidates see a successful 'dig' and assume DNS is fully working, not realizing that 'dig' with an explicit server bypasses the local resolver configuration, while 'host' relies on /etc/resolv.conf.
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
✓
The /etc/resolv.conf file is misconfigured.
The command 'dig @8.8.8.8 example.com' succeeds, proving that the DNS server at 8.8.8.8 is reachable and functional, and that network connectivity is fine. However, 'host example.com' fails because it uses the system's default resolver, which reads /etc/resolv.conf to determine which DNS server to query. If /etc/resolv.conf is misconfigured (e.g., missing or incorrect nameserver entries), the resolver cannot reach a valid DNS server, resulting in 'Host not found'.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The network interface is down.
Why it's wrong here
A down interface would break both queries, yet dig reaches 8.8.8.8 and resolves example.com. The fault lies in host's resolver configuration, not link state. Interface diagnostics belong to scenarios where no name resolution or connectivity succeeds at all, including direct queries to a specified server.
- ✗
The /etc/hosts file is corrupt.
Why it's wrong here
host consults the resolver configured in /etc/resolv.conf, so a corrupt /etc/hosts would not produce 'Host not found' while dig against 8.8.8.8 succeeds; the resolver configuration is the differing factor. It is tempting because /etc/hosts does affect name resolution, but only for entries it contains.
- ✗
The DNS server at 8.8.8.8 is not responding.
Why it's wrong here
dig @8.8.8.8 returned a response, proving that server answered the query; the failure lies with the resolver host itself uses. It is tempting because an unreachable DNS server is a common cause of resolution failure, but here the explicit query to that server already succeeded.
- ✓
The /etc/resolv.conf file is misconfigured.
Why this is correct
The `host` command queries the resolver configured in /etc/resolv.conf, whereas `dig @8.8.8.8` bypasses that file by querying the specified server directly. Since the explicit query succeeds, the resolver configuration must be faulty, satisfying the stem's constraint that only the default lookup path fails.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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