Sporadic name resolution failure happening on web service call

Question

One of our wcf service applications calls a seperate third party web service to submit information.

We are getting the following error every so often, but not all the time:
System.Net.WebException: The remote name could not be resolved: 'ws.examplesite.net' at System.Net.HttpWebRequest.GetRequestStream() at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)

The wierd thing is that after the error happens, we can hit "Submit" again a second later and it will go through just fine.

We have checked and double checked with our network guys and they have confirmed that DNS is correct, and they have done multiple nslookups in a row to confirm.

This is happening in all environments (dev, test and prod). We use the third party test and prod urls, and it is happening when we point to both.

Does anyone have any other trouble shooting techniques for this or any reason this would happen?

Much thanks, ~Ansley

Answer 1

The first thing I would do is get out WireShark or some other packet tracer and check excatly what is being sent when the web service request fails. That will straight away tell you whether a DNS request is failing or whether the web service request is being sent and it's a case of an incorrect error messge being reported. I'd suspect the former.

Answer 2

Name resolution could be failing for a reason not having directly to do with DNS. For instance, I had a name resolution failure today caused by the fact that the DNS query was issued after I lost my DHCP lease and before I got a new one. In effect, there was no connectivity to the DNS server at the time of the query.

Something like that (connectivity issue) could be your problem.

Answer 3

If the "network guys" use nslookup for debugging, it probably means they are not DNS experts. The best thing to do would be to post the actual domain name so we can test with better tools (dig, zonecheck, etc).