[SOLVED] www.google.com CNAME www.l.google.com

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Chris Corbyn
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[SOLVED] www.google.com CNAME www.l.google.com

Post by Chris Corbyn »

Code: Select all

;; ANSWER SECTION:
www.google.com.         331524  IN      CNAME   www.l.google.com.
www.l.google.com.       214     IN      A       216.239.59.103
www.l.google.com.       214     IN      A       216.239.59.104
www.l.google.com.       214     IN      A       216.239.59.147
www.l.google.com.       214     IN      A       216.239.59.99
Does anyone know if there's a practical reason why Google have CNAME'd http://www.google.com to http://www.l.google.com before they start the round robin? I only ask because I'm about to set up another cluster of servers which will round-robin but I can't see a reason to cname like this when it works if you just directly assign IPs to the actual domain. Unless maybe they use different domain names mapping to http://www.l.google.com without the end-user thinking about it.
Last edited by Chris Corbyn on Sun Aug 19, 2007 4:38 pm, edited 1 time in total.
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Chris Corbyn
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Post by Chris Corbyn »

I think I realised why they've done this. I ended up coming to the same result myself. Basically if you have different domain names virtualhosted on the same hardware then you don't want to have to list all round-robin IP addresses multiple times for each domain name. It's far easier to have one domain name containing all the A records for the round-robin, then link each virtual hosted domain name to that round-robin by linking it by CNAME. Effectively it's a more maintainable way to offer redundancy :)
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Oren
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Post by Oren »

I see... It's your monthly "self-discussion". Ok whatever, at least it took you just 2 posts this time. And as always, you solve the problem :wink:
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Chris Corbyn
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Post by Chris Corbyn »

My cries for help go unnoticed :( then I discover the answer or have a braindump and feel the need to keep the thread updated :P
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Benjamin
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Post by Benjamin »

I get a kick out it.
timvw
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Post by timvw »

I forgot to post the answer ;) (A while ago i found some forum where a guy explained it.. Also notice that the TTL of the records between google.com and x.google.com)
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Chris Corbyn
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Post by Chris Corbyn »

timvw wrote:Also notice that the TTL of the records between google.com and x.google.com)
Ah, I don't know why I didn't pick up on that. Good point, I should change our to do it that way. I just have all our TTL's set at 200 (even though a good chunk of DNS servers won't honour TTL properly :evil: )

There's definitely no need to have a low TTL on the alias though :)
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