In article <2m7rcvFk0v6qU1@uni-berlin.de>, "Madhur Ahuja" <firstname.lastname@example.org>
> I am a newbie, learning Domain Naming System(DNS). I want to know whether
> www.mail.yahoo.com is same as mail.yahoo.com.
barmar $ host www.mail.yahoo.com
www.mail.yahoo.com is an alias for rc.yahoo.com.
rc.yahoo.com is an alias for rc.yahoo.akadns.net.
rc.yahoo.akadns.net has address 18.104.22.168
rc.yahoo.akadns.net has address 22.214.171.124
rc.yahoo.akadns.net has address 126.96.36.199
barmar $ host mail.yahoo.com
mail.yahoo.com is an alias for login.yahoo.com.
login.yahoo.com is an alias for login.yahoo.akadns.net.
login.yahoo.akadns.net has address 188.8.131.52
They don't seem to be the same.
> Since www is a subdomain of
> it must be a different machine.
No it doesn't, but in this case it appears to be.
> Does it need to be on different IP address.
It could be if they wanted it to.
> I have seen cases where a
> subdomain such as www.site.com has same IP address as site.com. Is this
> normal. What kind of record
> is need to be created in DNS for this mapping.
Any name can be used for anything you want. If you want two names to
resolve to the same same address, just enter two A records with the same
address. You can also use aliases, as Yahoo does for some of their
names (akadns.net is used by Akamai for their load sharing/balancing
Barry Margolin, email@example.com
*** PLEASE post questions in newsgroups, not directly to me ***