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I'm having a strange issue on my initial lab setup. Situation: Host with OS Server 2008 R2 64bit, on this host a Virtual Machine in Hyper-V with OS Server 2008 SP1 32bit. The virtual machine has a fixed ip, and is referring to itself for the preferred DNS Server (dns server role has been installed). The host has tcp/ip set to automatic (so automatic ip from router, and dns/gateway = router). Both are able to ping each other on IP address (same ip range). Both are NOT able to ping each other on hostname (sounds logic because virtual machine dns server does not yet have a dns record for the hostmachine).

But here's the strange thing: I am able to set up a working network mapping on the Virtual Machine to the host: \\hostname\c$.

The first thing I thought was 'something' is blocking the ping request, so I completely disabled Windows Firewall on both Virtual Machine and host. Still pinging on hostname in both ways didn't work, yet I am able to access the network mapping on hostname. There is no extra software installed on both systems (clean windows server 2008).Can someone tell me what is causing this?

I always thought: ping on IP address works => network mapping on IP address works. Pinging on hostname doesn't work => network mapping on hostname doesn't work neither. Where am I wrong?

Looking forward to your advice!

sysadmin1138
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ciscokid
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  • Try using nslookup to first see if the host name resolves into the IP address -- and that it is indeed the correct IP address. Also try nbstat -a and nbtstat -A. – jftuga Jan 12 '11 at 21:56
  • Nslookup on the Virtual Machine is not working, because it is using a 'clean' dns server with no records in it (except itself). – ciscokid Jan 12 '11 at 21:58
  • Forgot to mention: only using 1 hardware network adapter and 1 virtual network to which the virtual machine is attached. IPv6 is unchecked on the Virtual Machine tcp/ip properties. – ciscokid Jan 12 '11 at 22:17
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    name resolution on Windows isn't limited to DNS. Netbios can (and does) send broadcasts to the entire local network of the form "who is `hostname`." `hostname` can respond to that, and resolution will work even with nary a DNS server. did you run the `nbtstat`s as mentioned by @jftuga? – Michael Lowman Jan 12 '11 at 22:26
  • I know name resolution is not limited to DNS. But I also know that if you ping a hostname the complete name resolving order (dns, wins, broadcast,...) is checked, and if you don't receive a reply on your ping request, name resolving is simply not working (so not only dns).I don't receive a reply when I ping on hostname. – ciscokid Jan 13 '11 at 08:28

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I had same problem, here's what resolved it. Make sure you enable both File and Printer Sharing inbound rules in: (1) Echo Request -ICMPv4-In and (2) NB-Name-In.

The NB-Name-In will allow NetBIOS broadcasts when the DNS query fails.

Grant
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