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Difficulty: HardIP Addressing Services

A network engineer is configuring core IP addressing services for an enterprise network. A new web-based portal service needs to be mapped to an existing server's canonical hostname, `host01.corp.internal`, which already resolves to an IPv4 address. Simultaneously, newly deployed IP telephony endpoints require a DNS mechanism to dynamically locate the hostname and port number of their primary Session Initiation Protocol (SIP) server. Which combination of DNS record types should the engineer configure to meet these requirements?

  1. A CNAME record for the web portal alias and an SRV record for the SIP server locationAnswer
  2. B
    An A record for the web portal alias and an MX record for the SIP server location
  3. C
    A CNAME record for the web portal alias and a PTR record for the SIP server location
  4. D
    An AAAA record for the web portal alias and a TXT record for the SIP server location

Answer

The configuration requires a CNAME record for the web portal alias and an SRV record for SIP server discovery.
The combination of a CNAME record and an SRV record satisfies both functional requirements. The CNAME record aliases the new portal service name to the host's primary canonical domain name, while the SRV record defines the server hostname, priority, weight, and port number for SIP telephony discovery.

Step-by-Step Solution

1
Identify the DNS requirement for domain name aliasing.
Mapping `portal.corp.internal` to an existing canonical hostname `host01.corp.internal` requires a Canonical Name (CNAME) record.
CNAME records allow an administrator to map multiple service names to a single canonical host name without duplicating underlying IP address records.
2
Identify the DNS requirement for dynamic service discovery including port specifications.
Locating a specific protocol service (SIP) and its active transport port requires a Service Location (SRV) record.
SRV records follow the format `_service._proto.name TTL class SRV priority weight port target`, enabling VoIP endpoints to discover both host location and port numbers dynamically.

Key Concept

DNS Record Selection and Service Location (SRV vs CNAME)
Estimated Time:2m 0s
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Topics

IP Addressing Services

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