A network technician is troubleshooting an issue on a Linux host that cannot resolve the hostname of an internal server `app.corp.local`. The technician runs `dig app.corp.local` and receives a response indicating `STATUS: SERVFAIL` from the local recursive DNS server at `192.168.1.2`. To determine whether the issue is isolated to the local recursive server or affects the authoritative server directly, the technician wants to query the domain's designated authoritative DNS server at `10.0.5.50`. Which of the following command-line entries should the technician execute?
- Adig app.corp.local -x 10.0.5.50
- Bdig app.corp.local AAAA
- dig @10.0.5.50 app.corp.localAnswer
- Dnetstat -an | grep 10.0.5.50:53
Answer
Executing `dig @10.0.5.50 app.corp.local` sends the query directly to the authoritative DNS server at `10.0.5.50`.
In the `dig` (Domain Information Groper) command-line utility, the `@` symbol followed by an IP address or hostname tells `dig` to send the query directly to that specific DNS server. Running `dig @10.0.5.50 app.corp.local` allows the technician to bypass the local recursive resolver (`192.168.1.2`) and evaluate the authoritative server's response.
Step-by-Step Solution
Key Concept
Directing DNS lookup queries to specific name servers using the `dig` utility