Using nslookup to verify DNS registration for domain controllers

The nslookup command is a standard command-line tool provided in most DNS service implementations. It offers the ability to perform query testing of DNS servers and obtain detailed responses as the command output. This information is useful in troubleshooting name resolution problems, verifying that resource records (RRs) are added or updated correctly in a zone, and debugging other server-related problems.

When trying to join a Windows 2003 DC using NetBIOS name, you may receive this message: “A domain controller for the domain could not be contacted”. Common issue with this error may due to the DNS SRV records required to locate a domain controller for the domain are not registered in DNS. These records are registered with a DNS server automatically when a domain controller is added to a domain.

To verify DNS registration for domain controllers, we may use the nslookup command

On your Command Prompt.

Type:

nslookup

After the previous command completes, at the nslookup (">") prompt type:

set q=srv

where srv is the service location (SRV) resource record.

After the previous command completes, type:

_ldap._tcp.dc._msdcs.Active_Directory_domain_name

For example, if the DNS domain name of your Active Directory domain is ipcnetworking.com, type:

_ldap._tcp.dc._msdcs.ipcnetworking.com.

The following is an example of command-line output for an Nslookup session, used to verify SRV resource records that are registered by domain controllers. In this example, the two domain controllers are dc1 and dc2 and are registered for the "domain.com" domain.

C:\nslookup
Default Server: ds.abc.com
Address: 10.0.0.1
set type=srv
_ldap._tcp.dc._msdcs.domain.com

Server: ds.abc.comm
Address: 10.0.0.1
_ldap._tcp.dc._msdcs.domain.com SRV service location:
priority = 0
weight = 100
port = 389
svr hostname = dc1.domain.com
_ldap._tcp.dc._msdcs.domain.com SRV service location:
priority = 0
weight = 100
port = 389
svr hostname = dc2.domain.com
dc1.domain.com internet address = 202.224.1.1
dc2.domain.com internet address = 202.224.1.2