ping -a parameter

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ping -a parameter

Post by Guest » Wed Jan 05, 2011 12:16 pm

Hi  everbody.

I was doing ping with parameter -a, when i encountered something strange.  here is what i did.





I got the  ip address from above command as


Then i used the command  :

ping -a


My understanding was  ping will also give me  host name because we are using parameter - a,  it did give me host name as:

I performed ip look up using



I  found entry as:


Here is my question,  when i clicked this link i was able to get to  ,thereby proving the ip address  is indeed mapped to www  But when i moved the cursor over"  right after the period between lb and cnet in the link, i was directed to

They are two complete host name mapped to How is it possible?


Also  when i pinged  i get the ip address as   .  But as mentioned above is mapped  to



May be i am not reading the mapping "" properly



thanks and have a good weekend.


Re:ping -a parameter

Post by Guest » Wed Jan 05, 2011 1:03 pm



These are the DNS lookups for the entries you are asking about -    PTR    300    CNAME    300    PTR    300



Note the second entry for is a CNAME and not a PTR like the other 2. A CNAME or Canonical Name record is simply a way to map one DNS name to another so if you enter "" then a DNS lookup is done and the response is This response will then be looked up again to get an IP address ie. the first entry above will provide this.


So its simply a way of having multiple "names" mapped to a DNS names eg.,, could if you wanted all be mapped to And that is why you are seeing multiple names mapped to the same IP.




Re:ping -a parameter

Post by Guest » Wed Jan 05, 2011 1:16 pm

Thanks Jon.

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