Testing the DNS Name Resolution

From SambaWiki
Revision as of 19:28, 5 March 2022 by Pgoetz (talk | contribs) (added host alternative)


To verify that your DNS settings are correct and your client or server is able to resolve IP addresses and host names use the nslookup command. The command is available on Linux and Windows.

Forward Lookup

To resolve a host name its IP address:

# nslookup DC1.samdom.example.com

Name:   DC1.samdom.example.com

alternatively you can use the command:

# host DC1.samdom.example.com
DC1.samdom.example.com has address

Reverse Lookup

To resolve a IP address to its host name:

# nslookup
Address:	name = DC1.samdom.example.com.

Note that in a Samba AD, the reverse zone is not automatically configured. To set up a reverse zone, see DNS Administration.

Resolving SRV Records

Active Directory (AD) uses SRV records to locate services, such as Kerberos and LDAP. To verify that SRV records are resolved correctly, use the nslookup interactive shell:

$ nslookup
> set type=SRV
> _ldap._tcp.samdom.example.com

_ldap._tcp.samdom.example.com	service = 0 100 389 dc2.samdom.example.com.
_ldap._tcp.samdom.example.com	service = 0 100 389 dc1.samdom.example.com.
> exit

Alternatively, you can use the host command.

$ host -t SRV _ldap._tcp.samdom.example.com
_ldap._tcp.samdom.example.com has SRV record 0 100 389 dc1.samdom.example.com.
_ldap._tcp.samdom.example.com has SRV record 0 100 389 dc2.samdom.example.com.

Error Messages

  • The DNS server is not able to resolve the host name:
** server can't find DC1.samdom.example.com: NXDOMAIN
  • The DNS server is not able to resolve the IP address:
** server can't find NXDOMAIN
  • The DNS server used is not available:
;; connection timed out; no servers could be reached