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Difficulty: MediumUtilizing Command-Line Network Troubleshooting Utilities

A network administrator is investigating a name resolution issue where workstations can reach an internal server via IPv4, but fail to resolve its IPv6 address using the internal DNS server at 10.0.10.510.0.10.5. The administrator needs to query the specified DNS server directly to verify if an IPv6 mapping exists for `app.lab.internal`.

Which TWO of the following command-line diagnostic utilities and syntax options will successfully query the targeted DNS server specifically for the host's IPv6 (AAAAAAAA) record? (Select TWO)

  1. dig @10.0.10.5 app.lab.internal AAAAAnswer
  2. nslookup -type=AAAA app.lab.internal 10.0.10.5Answer
  3. C
    nslookup -type=A app.lab.internal 10.0.10.5
  4. D
    netstat -an | grep 10.0.10.5:53

Answer

The commands 'dig @10.0.10.5 app.lab.internal AAAA' and 'nslookup -type=AAAA app.lab.internal 10.0.10.5' are both valid CLI invocations to query a specific DNS server for IPv6 AAAA records.
To diagnose IPv6 DNS lookup issues directly against a specific DNS server, network administrators use dedicated name resolution utilities (dig or nslookup). In dig, the syntax requires specifying the targeted DNS server with an '@' prefix (e.g., @10.0.10.5) followed by the domain name and record type AAAA. In nslookup, the '-type=AAAA' option specifies IPv6 record requests, and appending the target DNS server IP address at the end overrides the default local DNS resolver.

Step-by-Step Solution

1
Identify the required record type for IPv6 resolution.
IPv6 domain address resolution uses AAAA (quad-A) records, whereas IPv4 uses A records.
The scenario explicitly specifies diagnosing IPv6 resolution failure.
2
Identify command-line parameters for targeting a specific DNS server.
In 'dig', specifying '@server_ip' directs the lookup to that server. In 'nslookup', adding the server IP as a positional trailing argument targets that server.
The administrator must test the internal DNS server at 10.0.10.5 rather than relying on default system resolver configuration.
3
Evaluate the choices for syntax correctness and functionality.
Both 'dig @10.0.10.5 app.lab.internal AAAA' and 'nslookup -type=AAAA app.lab.internal 10.0.10.5' meet all criteria.
Both command structures correctly specify the record type and direct query target.

Key Concept

DNS Command-Line Diagnostics for IPv6 (AAAA Records)
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Topics

Utilizing Command-Line Network Troubleshooting Utilities

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