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Basic nslookup Operation - Quiz

Each question is worth one point. Select the best answer or answers for each question.
1. You run dig example.com with no additional options. What does the command actually do?
Please select the best answer.
  A. Returns operating system and machine architecture information for the host
  B. Performs a reverse lookup, mapping an IP address back to a host name
  C. Sends a recursive query to the resolver configured for the system and returns the A record
  D. Transfers the complete contents of the zone from its authoritative server

2. A dig response header reads flags: qr rd ra, with no aa flag. What does the missing aa tell you?
Please select the best answer.
  A. The information in the response is probably false
  B. The answer came from a resolver cache rather than from a server authoritative for the zone
  C. The query failed and no data was returned
  D. DNSSEC validation of the response failed

3. You need a complete list of every record in a zone you do not administer. What is the realistic outcome?
Please select the best answer.
  A. Run the ls command inside nslookup to list the zone
  B. Request a zone transfer with dig AXFR @ns1.example.com example.com, which nearly every server will refuse unless your address is permitted by allow-transfer
  C. Run dig ANY example.com, which returns the full contents of the zone
  D. Run resolvectl status, which lists the records the zone contains

4. dig example.com returns 192.0.2.10, but dig -x 192.0.2.10 returns a completely different host name. Why is this not necessarily a misconfiguration?
Please select the best answer.
  A. The reverse lookup failed and returned an unrelated cached record
  B. Forward and reverse records live in separate zones under separate administrative control, and nothing in DNS requires them to agree
  C. The -x option does not perform a real DNS query
  D. A PTR record must always match its A record, so the zone is broken

5. You changed a record an hour ago, but dig example.com still returns the old address, and the TTL in the answer section is lower on each repeated query. What does the decreasing TTL indicate?
Please select the best answer.
  A. You are being served a cached copy that will expire when the TTL reaches zero
  B. The zone file was never edited and the change must be made again
  C. The TTL shows how long the record has existed in the zone
  D. DNSSEC validation has invalidated the newer record

6. What does dig @ns1.example.com example.com +norecurse tell you that an ordinary query does not?
Please select the best answer.
  A. Whether the domain name is currently registered
  B. Exactly what that one server holds, with no cache in between, and an aa flag confirming the answer is authoritative
  C. It forces the local resolver to restart its lookup from the root servers
  D. It requests a full zone transfer from that server