XK0-004 · Question #287
A systems administrator wants to verify the DNS information of a system that is in production. Which of the following will provide this information?
The correct answer is C. dig -x 10.10.20.21 @10.10.1.10. The 'dig' command with the -x flag and @server notation is the correct tool to perform a reverse DNS lookup against a specific DNS server for verification.
Question
A systems administrator wants to verify the DNS information of a system that is in production. Which of the following will provide this information?
Options
- Anmap -R 10.10.20.21 10.10.1.10
- Bwhois -r -h 10.10.1.10 10.10.20.21
- Cdig -x 10.10.20.21 @10.10.1.10
- Droute 10.10.20.21 gw 10.10.1.10
How the community answered
(26 responses)- B4% (1)
- C92% (24)
- D4% (1)
Why each option
The 'dig' command with the -x flag and @server notation is the correct tool to perform a reverse DNS lookup against a specific DNS server for verification.
The 'nmap -R' flag enables DNS resolution during a port scan, but nmap is a network scanner and not a tool designed for targeted DNS record verification against a specific server.
The 'whois' command queries domain registrar databases for registration and ownership data, not DNS resource records stored on a particular DNS server.
The command 'dig -x 10.10.20.21 @10.10.1.10' performs a reverse DNS PTR record lookup for the IP address 10.10.20.21, directed specifically at the DNS server 10.10.1.10. The -x flag enables reverse lookup mode and the @ syntax designates the target DNS server, making this the precise method for verifying what DNS records a production DNS server holds for a given host.
The 'route' command manages and displays the kernel IP routing table and has no function related to DNS record lookups or DNS server queries.
Concept tested: Reverse DNS lookup verification using dig
Source: https://linux.die.net/man/1/dig
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