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Difficulty: HardIP Addressing Services

An enterprise network administrator is deploying a centralized Voice over IP (VoIP) telephony solution across multiple remote subnets. While legacy IP desk phones receive their server configuration via DHCP Option 150, newly deployed softphone clients rely on DNS to dynamically discover the hostname, port number (UDP 5060), and priority of the primary Session Initiation Protocol (SIP) server within the internal domain. Which DNS resource record type must be created to support this automated service discovery?

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

Answer

The SRV (Service) record is required because it maps a specific service name, transport protocol, and domain to the corresponding target hostname, port number, priority, and weight.
SRV (Service Location) records enable network clients to locate specific services using standardized symbolic names. They explicitly contain fields for priority, weight, port number, and target hostname, allowing applications like SIP softphones to dynamically locate servers on non-standard or standard ports without manual end-user configuration.

Step-by-Step Solution

1
Analyze the technical requirements of the scenario
The application requires dynamic discovery of a service host, port number (UDP 5060), and service protocol (SIP).
Standard host records (A/AAAA) only resolve names to IP addresses without specifying transport layer port numbers.
2
Evaluate DNS record capabilities
SRV records are formatted specifically as `_service._proto.name. TTL CLASS SRV priority weight port target.` to provide protocol and port information alongside host details.
Only SRV records include port protocol bindings natively within DNS infrastructure.

Key Concept

DNS Record Types and Service Discovery (SRV Records)
Estimated Time:1m 30s
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Topics

IP Addressing Services

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