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Difficulty: EasyUtilizing Command-Line Network Troubleshooting Utilities

A network technician suspects that a workstation's local DNS resolver is returning cached, out-of-date IP addresses for an internal server. The technician needs to test name resolution by sending a DNS query directly to a specific authoritative name server rather than relying on the local resolver configuration. Which command-line utility should the technician use to perform this direct query?

  1. nslookupAnswer
  2. B
    ping
  3. C
    netstat
  4. D
    ipconfig

Answer

The correct utility is nslookup, which allows targeted DNS server queries and record inspection.
The nslookup command (along with dig) is designed specifically to test and troubleshoot DNS infrastructure. It allows technicians to query specific name servers by IP address or hostname, view specific record types (A, AAAA, MX, CNAME), and bypass local DNS client cache settings.

Step-by-Step Solution

1
Identify the diagnostic requirement
The requirement is to send a direct DNS query to a specific target DNS server to test domain name resolution without using local cached results.
Testing specific DNS server responses requires a command-line tool dedicated to name resolution lookup.
2
Evaluate candidate CLI network utilities
The nslookup command (or dig on Linux/macOS) accepts a specified DNS server IP address as an argument (e.g., nslookup hostname server_ip) to perform explicit targeted queries.
Other utilities rely on operating system default socket calls or serve completely different diagnostic purposes like layer 3 pinging or protocol stat tracking.

Key Concept

Direct DNS Querying using CLI Utilities
Estimated Time:45s
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Topics

Utilizing Command-Line Network Troubleshooting Utilities

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