Question

Difficulty: EasyTroubleshooting DNS and Name Resolution Services

A network administrator is troubleshooting a user workstation that cannot connect to an internal website named `server1.corp.local`. The technician runs the `nslookup` command on the workstation and receives the following output:

C:\Users\User> nslookup server1.corp.local
Server: dc01.corp.local
Address: 10.0.0.10

*** dc01.corp.local can't find server1.corp.local: Non-existent domain

Which of the following is the most likely cause of this name resolution failure?

  1. The host name `server1.corp.local` does not have a corresponding A record configured on the DNS server.Answer
  2. B
    The DNS server at 10.0.0.10 is offline and failing to receive UDP port 53 network traffic.
  3. C
    The workstation is misconfigured to send standard DNS client queries over TCP instead of UDP.
  4. D
    The DNS server requires an MX record rather than an A record for IPv4 internal host resolution.

Answer

The host name does not have a corresponding A record configured on the DNS server.
The output explicitly demonstrates that the client reached the DNS server at `10.0.0.10`, which answered with a 'Non-existent domain' (NXDOMAIN) status. This indicates that the DNS server is working correctly but lacks an A record mapping `server1.corp.local` to an IP address.

Step-by-Step Solution

1
Analyze the command-line utility output from nslookup.
The local workstation successfully contacted the primary DNS server `dc01.corp.local` at IP address `10.0.0.10`.
Establishing that the DNS server responded rules out basic network reachability issues and offline DNS server failures.
2
Interpret the specific error message provided by the DNS server.
The server returned `Non-existent domain` (NXDOMAIN).
This error means the DNS server checked its zone database for `server1.corp.local` but found no matching address record.
3
Determine the necessary administrative resolution.
Create a valid A (IPv4) host record for `server1.corp.local` on the DNS server.
Adding the missing resource record directly resolves the NXDOMAIN error and enables proper hostname lookup.

Key Concept

DNS Host Record (A Record) Verification and NXDOMAIN Error Diagnosis
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