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Zorluk: ZorTroubleshooting DNS and Name Resolution Services

A network administrator deployed a new internal database server named `db-primary` with IP address 172.16.45.10172.16.45.10 inside the `internal.corp.net` DNS zone. Users situated on workstations within the `sales.corp.net` domain report that querying short hostname `db-primary` fails, whereas querying the fully qualified domain name (FQDN) succeeds.

The administrator executes the following troubleshooting commands from a user workstation in `sales.corp.net`:

C:\> nslookup db-primary
Server: dc1.sales.corp.net
Address: 172.16.10.5

*** dc1.sales.corp.net can't find db-primary: Non-existent domain

C:\> nslookup db-primary.internal.corp.net
Server: dc1.sales.corp.net
Address: 172.16.10.5

Name: db-primary.internal.corp.net
Address: 172.16.45.10

Which of the following configuration changes will resolve the short hostname resolution failure for all workstations in `sales.corp.net`?

  1. Append internal.corp.net to the DNS domain search list distributed to workstations via DHCP Option 119.Cevap
  2. B
    Add a CNAME record in the sales.corp.net DNS zone mapping internal.corp.net to db-primary.
  3. C
    Configure workstation resolver settings to force short hostname lookup queries over TCP port 53 instead of UDP port 53.
  4. D
    Flush the local client DNS resolver cache using the ipconfig /flushdns command on affected workstations.

Cevap

Append internal.corp.net to the DNS domain search list distributed to workstations via DHCP Option 119.
When a client queries a single-label short hostname (such as 'db-primary'), the operating system resolver appends domain suffixes from its DNS suffix search list. Because the target host resides in 'internal.corp.net' and the workstations belong to 'sales.corp.net', the client fails to resolve the host unless 'internal.corp.net' is appended to the workstation's search list. Distributing this suffix via DHCP Option 119 resolves the problem for all clients automatically.

Adım Adım Çözüm

1
Analyze the CLI output for short name vs FQDN queries.
The query for 'db-primary' returns NXDOMAIN (Non-existent domain) under 'sales.corp.net', while 'db-primary.internal.corp.net' resolves successfully.
The client operating system only appends its primary domain suffix ('sales.corp.net') when attempting to resolve single-label short names.
2
Determine the necessary mechanism to resolve single-label names across multi-domain environments.
Adding 'internal.corp.net' to the client's DNS suffix search list instructs the resolver to append 'internal.corp.net' if the initial local domain lookup fails.
Resolvers iterate through configured search suffixes sequentially when presented with single-label hostnames.
3
Select the centralized administrative fix for network-wide deployment.
Configuring DHCP Option 119 (Domain Search Option) ensures all client workstations dynamically receive the required suffix list.
Centralized DHCP option management updates all workstations without requiring manual static IP or adapter reconfiguration on individual hosts.

Anahtar Kavram

DNS Suffix Search List & Unqualified Hostname Resolution
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Troubleshooting DNS and Name Resolution Services

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