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Question

Difficulty: MediumIP Addressing Services

A network administrator is configuring a Domain Name System (DNS) server to support an automated security monitoring system. The monitoring system captures IP addresses from network traffic logs and performs reverse DNS lookups to convert those IP addresses back into hostnames. Which DNS record type must be created on the server to enable this reverse resolution functionality?

  1. PTR recordAnswer
  2. B
    AAAA record
  3. C
    CNAME record
  4. D
    SRV record

Answer

PTR record
A Pointer (PTR) record is specifically designed for reverse DNS lookups, mapping an IP address (in the in-addr.arpa or ip6.arpa domain) back to a Fully Qualified Domain Name (FQDN). This fulfills the requirement for the security monitoring tool to resolve logged IP addresses into readable hostnames.

Step-by-Step Solution

1
Identify the primary functional requirement from the scenario
The system needs to perform reverse DNS lookups (mapping an IP address to a hostname).
Security logging and network management tools use reverse DNS to identify hostnames associated with captured IP addresses.
2
Evaluate DNS record types against the reverse resolution requirement
Pointer (PTR) records reside in reverse lookup zones (in-addr.arpa for IPv4, ip6.arpa for IPv6) and explicitly map IP addresses to hostnames.
Forward lookup records (A, AAAA, CNAME) map hostnames to IP addresses or other hostnames, whereas PTR records perform the inverse mapping.

Key Concept

DNS Record Types and Reverse DNS Resolution
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Topics

IP Addressing Services

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