You want to ask the specific name server 8.8.8.8 for the MX records of example.com, bypassing whatever is configured in /etc/resolv.conf. Which command does this?
LPIC-1 Exam 102-500, objective 109. Networking fundamentals medium
Draft — not checked yet. This question was written from the published exam objectives and cites the clause it comes from, but nobody has yet read it against that clause and signed for it.
It is kept out of search results and out of mock exams until they have. Read the source below before you take the answer as settled.
The options
Not correct dig example.com MX 8.8.8.8
Wrong. Without the @ prefix, 8.8.8.8 is read as another name to look up, so dig queries your configured resolver for both example.com and the name 8.8.8.8.
Correct dig @8.8.8.8 example.com MX
Correct. The @server argument names the server to query, followed by the name and then the record type.
Not correct dig -s 8.8.8.8 -t MX example.com
Wrong. dig has no -s option for choosing a server; the server is always given as @server. (-t TYPE is a valid way to state the record type.)
Not correct getent hosts example.com MX
Wrong. getent hosts queries the NSS hosts database and only ever returns addresses. It cannot request a record type and cannot target a particular server.
Why
dig's argument order is `dig [@server] name [type]`. Both `dig @8.8.8.8 example.com MX` and `dig @8.8.8.8 -t MX example.com` work. The equivalent with host is `host -t MX example.com 8.8.8.8`, where the server is the trailing positional argument, and with nslookup it is `nslookup -type=MX example.com 8.8.8.8`.
Where this comes from
- Cited
- manual page dig(1)
Practise this
Reading one question is not practice. The trainer will draw a set from objective 109 and space the ones you get wrong.