unable to ping hostname, but \\hostname\c$ works?

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!