Windows 7 Stopped Using hosts file for DNS Resolution

Question

I am running Windows 7 Home Premium 64-bit. Starting today, I noticed that DNS resolution is not reading my %SYSTEMROOT%\System32\drivers\etc\hosts file. I say this because I added two new entries to the file and when I run 'nslookup' on the command line, they don't resolve. Further, just trying to resolve 'localhost' results in my primary DNS server being queried.

I've read several threads that suggest that the file might have been corrupted and to move it aside and create a new one. I've done that, and no improvement.

Is there some sort of registry key that controls the sequence of resources used for DNS resolution (similar to nsswitch.conf on UNIX)? What else could be causing this?

Thanks in advance.

Answer 1

When you run an nslookup on an address, windows will query the DNS server, and won't look in the hosts file. Always. However, when it actually goes to connect, it will use the host files value. Try adding example.com to your hosts file, and have it point to 127.0.0.1. Run an nslookup: it will resolve to the actual IP. Ping it. Your localhost will respond.

C:\>nslookup example.com
Server:  
Address:  10.110.5.1

Non-authoritative answer:
Name:    example.com
Address:  192.0.32.10


C:\>ping example.com

Pinging example.com [127.0.0.1] with 32 bytes of data:
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128

Ping statistics for 127.0.0.1:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 0ms, Average = 0ms

C:\>