WINS and DNS Integration in Windows 2003
If you must have a WINS server, then at least achieve the best configuration possible. Take the situation where the WINS database contains records for computers that DNS does not know about. It costs very little to configure DNS to query WINS for such NetBIOS names.
Topics for WINS and DNS Integration
- Configuring DNS for WINS Integration
- How the Integration Works
- Guy’s Challenges
- WINS and DNS Summary
WINS and DNS are full of surprises. For instance, to integrate WINS and DNS go to the zone folder not the server icon. It was a long time before I realized the significance of going to WINS tab in DNS and checking the box: ‘Use WINS forward lookup’. In fact, I was adding a special WINS record to the DNS forward lookup zone. However, once I had configured this tab, it was less of a shock to realize that I could carry out a similar procedure for in the Reverse Lookup zone. The result was I had integrated WINS and DNS for both zones.
When a DNS client send a name resolution query to the DNS server, the first thing the server does is look in its DNS zones to try and resolve the request. If it fails to find a name match, DNS strips down the fully qualified domain name to just the hostname, and passes a request for that name to the WINS server. If WINS finds such a name amongst its records, it sends back the name and IP address to DNS. And finally, DNS replies with answer to the client’s query.
Here is a fun challenge to test WINS / DNS integration. I assume that you already have DNS and WINS installed, and crucially, you configure the WINS tab on the DNS server to, ‘Use WINS for forward Lookup’. OK, here is the challenge, add a fictitious computer as a static entry in your WINS database. Ping that NetBIOS name. You should get a timed out reply, but interestingly, you should see the fictitious IP address that ping is attempting to connect. So this proves that ping at least, is using WINS.
Example 1. At the WINS server, add a static entry for PeterComputer 192.168.0.89.
At the command prompt: Ping PeterComputer
Result pinging petercomputer.cp.com [192.168.0.89]
The second half of the challenge is to add another record, but this time in DNS.
Example 2: In DNS Forward Zone, add PeterComputer 192.168.0.71
Result pinging petercomputer.cp.com [192.168.0.89] hmmm 89.
Humour me, run ipconfig /flushdns and try once more
Result pinging petercomputer.cp.com [192.168.0.71] hooray! 71.
What does experiment this prove? Well it shows that DNS clients can use their DNS server to retrieve information form the WINS database. My challenge also showed that DNS queries its own database before forwarding the request on to WINS. Incidentally, the challenge reminds us of ipconfig /flushdns.
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If you are going to use a WINS server, you may as well take advantage of the wonderful DNS system and just integrate WINS. The idea is that if DNS knows the answer to a clients query then it will reply immediately. However if it cannot resolve the NetBIOS name, it passes the query on to the WINS server. Any reply is then relayed to the original client.
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