Testing A WINS Server

On a CIFS/SMB domain the WINS service is critical for proper function [some things use WINS, some things use DNS, it is terribly confusing, but it is what it is]. DNS is relatively easy to test and you will likely know right away if it isn't working. But before adding those new DCs to your dhcpd.conf file -

option netbios-name-servers 192.168.1.78, 192.168.1.79, 192.168.1.65;

... it would be nice to be equally confident WINS is operating as expected.

To that end the Samba package provides a useful tool nmblookup which support querying of a WINS server much like host/nslookup does for DNS.

$ nmblookup --unicast=192.168.1.65 --recursion arabis-red
querying arabis-red on 192.168.1.65
192.168.1.58 arabis-red<00>
$ nmblookup --unicast=192.168.1.78 --recursion arabis-red
querying arabis-red on 192.168.1.78
192.168.1.58 arabis-red<00>
$ nmblookup --unicast=192.168.1.79 --recursion arabis-red
querying arabis-red on 192.168.1.79
192.168.1.58 arabis-red<00>

The ---unicast option specifies the IP address of the WINS server; but this option is only effective in the expected way if used with the [oddly named] --recursion options. Without --recursion the --unicast will not cancel use of the NetBIOS name resolution logic.

One other useful feature of nmblookup is the --translate option. This option invokes a reverse DNS search on the IP address returned by the WINS query - allowing one step verification that WINS and DNS are on the same page.

$ nmblookup --unicast=192.168.1.79 --translate --recursion arabis-red
querying arabis-red on 192.168.1.79
ARABIS-RED.example.com, 192.168.1.58 arabis-red<00>