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Difficulty: MediumUtilizing Command-Line Network Troubleshooting Utilities

A network administrator is investigating a database connection issue on a host machine. The administrator needs to query the designated internal DNS server at 10.0.0.5310.0.0.53 directly for the record `db1.corp.internal` rather than relying on local resolver cache settings, and also inspect all active TCP socket connections along with listening ports on the local system. Which of the following command-line entries will successfully achieve these goals? (Select TWO)

  1. Run `nslookup db1.corp.internal 10.0.0.53` to direct the name resolution query to the specific internal server.Answer
  2. B
    Run `dig -x 10.0.0.53 db1.corp.internal` to perform a forward A record query against the internal server.
  3. Run `netstat -an` to display all active connections and numerical port bindings.Answer
  4. D
    Run `arp -a 5432` to view active socket state information and TCP port bindings.

Answer

The correct actions are running `nslookup db1.corp.internal 10.0.0.53` to query the specific DNS server directly and running `netstat -an` to inspect active socket connections and listening ports numerically.
Directing an `nslookup` request to a specific server IP address (such as `nslookup db1.corp.internal 10.0.0.53`) bypasses local DNS caches to query that server directly. Additionally, `netstat -an` provides a detailed list of all listening ports and established socket connections using numerical IP addresses and port numbers.

Step-by-Step Solution

1
Identify the CLI tool syntax required to bypass local resolver settings and query a designated DNS server directly.
Executing `nslookup <hostname> <server_ip>` sends the lookup query explicitly to the specified server IP address (10.0.0.5310.0.0.53).
Default `nslookup` queries rely on configured system resolvers unless an explicit server address parameter is provided.
2
Identify the CLI utility suited for displaying open network ports and active TCP sessions.
`netstat -an` outputs all active TCP/UDP connections and open listening ports in numerical format.
The `-a` flag includes listening ports and the `-n` flag suppresses hostname/service resolution for faster numerical rendering.

Key Concept

Utilizing command-line network utilities (`nslookup`, `netstat`, `dig`, `arp`) for protocol inspection and reachability troubleshooting.
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Utilizing Command-Line Network Troubleshooting Utilities

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