Quick Tip: Fix “Ping request could not find host” when NSLookup still works

Recently I have run across this issue in a couple of different virtual environments and have only found the fix today! I saw some strange behaviour where my virtual server was unable to ping another server in my virtual environment with the error: “Ping request could not find host server.domain.com”, but when I run an NSLookup for the same address, it works fine. The example below is from a lab environment I have set up for Lync Server 2013.

First of all, I am using DNS Load-Balancing for a pool of 2 servers in my Lync Server environment. The pool is called Pool1 and is comprised of the servers with IP Addresses 192.168.182.128 and 192.168.182.131. When I ping pool1.mikeparker365.co.uk I get the error I mentioned earlier – see screenshot below:

PingError1

So I tried an NSLookup, expecting to find no response, but actually received both DNS entries for my Pool1 machines:

PingError2.PNG

This confused me – so I did some digging on the internet to see if I could find a quick fix!

I actually resolved the issue after some research by running the following commands in order (in an elevated command line window):

netsh winsock reset catalog
netsh int ip reset reset.log
ipconfig /flushdns
ipconfig /registerdns

Upon further testing I have found some eratic behaviour when running the commands, sometimes resolving and sometimes after the second, but in order to keep your environment clean I would recommend you run all 4 commands.

If you have any questions, comments or suggestions please either leave a comment below, Tweet me@MikeParker365 or email me at blog@mikeparker365.co.uk.

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