Windows

The most likely answer is that a router or firewall in your path to the Internet filters ICMP packets as a security measure.

A router en route to a Web site can be set up this way so the site is reachable using http protocol on port 80 but if youwere to ping by either IP address or hostname, you would get no response because it doesn't respond to the ICMP packets sent out by PING.

It does make troubleshooting more challenging, however, since PING is a time-honored way to testing connectivity to a particular IP address.

paul

I agree with Paul.
You may also try from command prompt:

tracert www.techrepublic.com

This will trace your route to destination address.
However, this will also fail if you are behind firewall.

Thanks a lot for the answers guys!

Like you said maybe ICMP packets are filtered but If the ICMP packets were filtered I should not be able to ping any address but I can ping some like www.yahoo.com and can't ping some like www.aol.com.

I am looking for the answer for the knowledge and curiosity. If somebody can explain it further I will be grateful.

some site stopped reply to ICMP packets to stop denial-service attack

I get the same results from pinging the 2 sites you mentioned (Yahoo pings AOL does not). I just got my DSL line installed, and put in a Linksys router (Very cheap, and has passed many security tests so far, and a truly Plug and Play configuration.) While going through the router manual (Yea, so I am that kind of Geek) they state that the router can block WAN requests which blocks the ping utility. Apparently this is becoming more and more common, especially with D.O.S. attacks and the like.

So, it is not your firewall that is causing this
FYI:
Ping times out to www.aol.com but gives the 205.188.146.23 IP adderss.
Tracert www.aol.com hops 14 times before getting the message that the destination hosts in unreachable.

Long live Ping!

Hope this sheds some light.

Beef

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