A new internal zone has been loaded on the name server 192.0.2.53, but the workstation you are sitting at still uses the old resolvers listed in /etc/resolv.conf. Which command asks that one server directly for the A record of db01.example.com?
LPIC-1 Exam 102-500, objective 109. Networking fundamentals easy
Machine-checked — no person has signed for it. This question was read against the source cited below by an automated pass, which found no contradiction. That is a weaker claim than it sounds: the same kind of process wrote the question, so it can confirm its own mistake.
Treat it as a good draft rather than as settled fact, and read the source below before you rely on it. It is not used in mock exams here — only questions a person has signed for are.
How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
The options
Correct dig @192.0.2.53 db01.example.com
Correct. An argument beginning with @ names the server dig sends the query to, overriding the nameserver lines in /etc/resolv.conf for that one lookup.
Not correct dig db01.example.com +nssearch
Wrong. +nssearch finds the authoritative servers for the enclosing zone and queries each of them for the SOA record; it does not let you name the server you want.
Not correct dig -x 192.0.2.53 db01.example.com
Wrong. -x turns the address into a reverse (PTR) lookup under in-addr.arpa, and the trailing name is then parsed as a second, separate query. dig sends both to the resolvers in /etc/resolv.conf; nothing here targets 192.0.2.53 as a server.
Not correct dig +trace db01.example.com
Wrong. +trace walks the delegation from the root servers downwards using iterative queries; it still starts from the resolvers in /etc/resolv.conf and never targets a server you choose.
Why
dig takes the server to query as an argument prefixed with @, given either as an address or a name. Without it, dig reads the nameserver lines from /etc/resolv.conf, which is exactly what you want to bypass when testing a server that is not yet in the client configuration. Note that @ selects the transport target, while -x, +trace and +nssearch all change what is being asked rather than who is being asked.
Where this comes from
- Cited
- manual page dig(1)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 109 and space the ones you get wrong.
More questions on this objective
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