1

I can $ping google.com and get data back

PING google.com (74.125.227.96): 56 data bytes
64 bytes from 74.125.227.96: icmp_seq=0 ttl=56 time=26.939 ms
64 bytes from 74.125.227.96: icmp_seq=1 ttl=56 time=23.739 ms

But I can't ping the www subdomain.

$ ping wwww.google.com
PING wwww.google.com (92.242.140.2): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
^C
--- wwww.google.com ping statistics ---
3 packets transmitted, 0 packets received, 100.0% packet loss

Why is that?

3
  • I am able to ping both just fine. I am unable to ping that specific IP though (94.242.140.2) possibly because that IP doesn't respond to pings.
    – mmtauqir
    Sep 17, 2014 at 2:50
  • 3
    You pinged the subdomain wwww (four times w) instead of www, right? Sep 17, 2014 at 4:39
  • a reverse lookup of 94.242.140.2 gives: 2.net-94.242.140.kaluga.ru
    – Anthon
    Sep 17, 2014 at 5:14

1 Answer 1

4

Google is using a lot of different servers and is doing load balancing between them using different DNS entries. If a single server dies another server will do its work.

You can use the host command to look at your DNS configuration. My ISP currently resolves "www.google.com" as:

$ host www.google.com
www.google.com has address 173.194.32.240
www.google.com has address 173.194.32.241
www.google.com has address 173.194.32.242
www.google.com has address 173.194.32.243
www.google.com has address 173.194.32.244
www.google.com has IPv6 address 2a00:1450:4008:801::1011

But different DNS servers will resolve it differently:

$ host www.google.com 8.8.8.8
Using domain server:
Name: 8.8.8.8
Address: 8.8.8.8#53
Aliases: 

www.google.com has address 74.125.232.19
www.google.com has address 74.125.232.17
www.google.com has address 74.125.232.16
www.google.com has address 74.125.232.20
www.google.com has address 74.125.232.18
www.google.com has IPv6 address 2a00:1450:4016:804::1013

The IP adresses (like the corresponding servers) will change from DNS server to DNS server and from time to time.

Maybe in your case your DNS server contained one entry to a dead server. Your browser is normally smart enough to try one of the other addresses in such a case.

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