Question

Difficulty: MediumDNS Infrastructure and Record Types

A network administrator is organizing corporate DNS infrastructure records to ensure proper service resolution and security compliance. Match each DNS resource record type on the left with its correct functional description on the right.

  • SRV RecordDefines the hostname and specific port number used by network services such as SIP or LDAP.
  • PTR RecordMaps an IP address to a canonical domain name for reverse DNS resolution queries.
  • CNAME RecordCreates an alias mapping one domain name to another existing canonical domain name.
  • TXT RecordStores descriptive text data used for domain ownership validation and email authentication rules like SPF and DKIM.

Answer

SRV Record matches the definition of host and port location for services; PTR Record matches reverse DNS resolution from IP to domain; CNAME Record matches domain aliasing to another domain; TXT Record matches storing arbitrary text strings for email authentication like SPF and DKIM.
Each DNS record type has a dedicated function: SRV locates service protocols and port numbers; PTR enables reverse resolution of IP addresses to hostnames; CNAME acts as a domain alias pointing to another hostname; and TXT stores text metadata such as SPF and DKIM authentication signatures.

Step-by-Step Solution

1
Analyze SRV Record functionality
Identifies that SRV specifies hostnames along with port numbers and service protocols (e.g., SIP, LDAP).
SRV records are unique among standard records because they include protocol and port metadata.
2
Analyze PTR Record functionality
Identifies that PTR performs reverse mapping of IP addresses to canonical domain names.
PTR records populate reverse lookup zones.
3
Analyze CNAME Record functionality
Identifies that CNAME points an alias hostname to another canonical DNS name.
CNAME allows multiple subdomains to share the target canonical host resolution.
4
Analyze TXT Record functionality
Identifies that TXT contains freeform text strings used by protocols like SPF and DKIM for security verification.
TXT records provide human and machine readable metadata without altering routing.

Key Concept

DNS Resource Record Functions and Applications
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