Question

Difficulty: HardDNS Infrastructure and Record Types

An enterprise network administrator is auditing the organization's external DNS zone files and service discovery settings. Match each DNS resource record type on the left with its correct primary technical function or scenario application on the right.

  • SRV RecordSpecifies hostname, port number, priority, and weight for specialized service discovery such as SIP or LDAP.
  • PTR RecordMaps an IP address to a canonical hostname for reverse DNS queries and anti-spam validation.
  • SOA RecordDefines primary name server authority, zone serial numbers, and zone transfer refresh/retry timers.
  • TXT RecordStores arbitrary text strings used for email authentication mechanisms such as SPF, DKIM, and DMARC.

Answer

The correct pairings link SRV records to service locator parameters (port, priority, weight), PTR records to reverse IP-to-hostname resolution, SOA records to zone authority and timing metadata, and TXT records to published email security key and policy strings.
Each DNS record type provides distinct functionality: SRV for service locator metadata with port and priority parameters; PTR for reverse IP address mapping; SOA for governing zone administrative metadata and transfer timing; and TXT for hosting email authentication policies like SPF and DKIM keys.

Step-by-Step Solution

1
Analyze SRV record attributes
Identify that SRV records uniquely incorporate symbolic service names, protocols, priorities, weights, and target destination ports.
Standard hostname-to-IP records do not embed layer-4 transport port numbers or load balancing weights.
2
Evaluate PTR record operation
Associate PTR records with reverse lookup resolution mapping IP addresses back to domain names.
Reverse resolution relies on pointer records stored within specialized reverse DNS zones.
3
Inspect SOA record zone parameters
Match SOA records with zone transfer timers, administrator email addresses, primary authority designation, and zone serial number updates.
The Start of Authority record governs administrative metadata and secondary server zone transfer behavior.
4
Examine TXT record security applications
Connect TXT records to SPF validation policy strings and DKIM public key distribution.
TXT records act as flexible text containers heavily leveraged by anti-spoofing and domain authentication standards.

Key Concept

DNS Resource Record Functions and Applications
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