Im trying to find out where the problem is, but I'm having problems reached quite some hosts. Some IPs I cannot ping and some IPs I can ping but that IP cannot ping or tracert me.

E.g. I cannot Ping the random IP 87.81.228.15, however I can tracert it untill it stops responding after a few hops.

any idea what is wrong? Is it my ISP?

ping command only works for the same IP class (eg: 192.168.x.x), you cannot ping a computer in a different IP class! tracert traces the route to the host you specify, no matter the IP class or workgroup name. anyway, why do you want to ping and tracert hosts?

its possible that the ip is part of an ISP's subnet and isnt actually being used by one of their customers, you wouldnt be able to ping it but you would be able to tracert it upto the subnet its contained on.. i think

either that or that ip is not responding to ICMP packets, hence you not being able to ping it

I typed out a long descriptive response here and then MSFN's server problems wiped it out

Short version. If a firewall is blocking ICMP traffic you cannot ping. It does not matter what IP "class" you're in either, you can ping from a class C to a class A, etc. Don't really know where he got that info from.

You may want to try the "pathping" command too.

20 years ago....just 20 years ago....people'd be asking "what's a ping?"...I guess some still do.