I have been able to work around my issue, so I am not looking for a solution, but I am looking for an answer as to why I am seeing the behaviour as described here:
Context: I'm developing an application that uses a software component to relay email messages out, using a local SMTP server component. I'm on a Windows 7 dev machine on a residential broadband connection behind a Virgin Media Super Hub router.
The component requires that I specify a DNS address for domain name resolution. Initially, I used the DNS server address as specified in my TCP/IPv4 connection properties. My attempts to relay email failed with a time out at domain name resolution.
I used cmd window "
nslookup www.google.com". This failed with a time out:
So I used "
ipconfig/all" to check name servers again. The name server is reported as being at address 192.168.0.1
At this point my internet connection is working as normal, so I change my TCP/IPv4 connection properties to "Obtain an IP address automatically" and "Obtain an DNS server address automatically".
Following this, I test SMTP relay, and it works.
I use "
ipconfig/all" again, and find that my name servers are now reported as:
Now I change my TCP/IPv4 connection properties back to the fixed settings as before.
Providing that I continue to specify 18.104.22.168 as the name servers in my SMTP relaying application, everything works, despite Windows being configured to use 192.168.0.1.
I don't like not understanding why:
- I'm unable to check the DNS server that is in use using standard cmd methods.
- Why windows appears to be using a different DNS server address to that which is configured.
Could anyone address the above points, and also answer my question here:
- Is it possible that my router is translating DNS addresses for some types of query, but not for others?
Any light that can be shed here is appreciated!