NSLOOKUP query

Hi all,

When I do an NSLOOKUP on google.com, I get three IP addresses as below

Non-authoritative answer:
Name: google.com
Addresses: 64.233.167.99, 64.233.187.99, 72.14.207.99

When I do an NSLOOKUP on www.google.com, I get this:

Non-authoritative answer:
Name: www.l.google.com
Addresses: 64.233.167.104, 64.233.167.147, 64.233.167.99
Aliases: www.google.com

Firstly, why are there three addresses linked to "google.com"?
Why is one IP address shared between www.google.com and google.com?

Is it something to do with CNAME entries in the DNS?

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Comments

royal

google.com will be the server that is hosting the google.com dns. It is google's authoritative servers and there are more than one for redundancy. www.google.com of course is the server that is hosting the web pages. Again, there are more than one web servers that are hosting Google's web pages for redundancy.

The following 3 dns servers contain the google.com authoritative google.com dns zones:
64.233.167.99, 64.233.187.99, 72.14.207.99

The following 3 servers contain web server software such as IIS, Apache, or something else that hosts Google's web pages for public use:
64.233.167.104, 64.233.167.147, 64.233.167.99

In this case: 64.233.167.99 is both a dns server and a web server. For the google.com dns zone, there is an NS record for 64.233.167.99 and an A record that points www to 64.233.167.99.

plettner

Thanks. That's cleared it up. I thought it may be to do with reduncancy but I didn't undertsand why www.google.com would have three entires. It's clear now.

royal

plettner wrote:

Thanks. That's cleared it up. I thought it may be to do with reduncancy but I didn't undertsand why www.google.com would have three entires. It's clear now.

Glad I could clear that up for you. You can believe that there are definitely more than 3 web servers also for Google. Basically, what they do, is have 3 server farms (data centers). Each of those ip addresses are actually the ip address for 3 separate Network Load Balance Clusters. This ensures additional redundancy.

sprkymrk

http://dondodge.typepad.com/the_next_big_thing/2006/06/google_data_cen.html

Today even the closest Google watchers have lost precise count of how big the system is. The best guess is that Google now has more than 450,000 servers spread over at least 25 locations around the world.

http://www.baselinemag.com/print_article2/0,1217,a=182560,00.asp

Google runs on hundreds of thousands of servers—by one estimate, in excess of 450,000—racked up in thousands of clusters in dozens of data centers around the world. It has data centers in Dublin, Ireland; in Virginia; and in California, where it just acquired the million-square-foot headquarters it had been leasing. It recently opened a new center in Atlanta, and is currently building two football-field-sized centers in The Dalles, Ore.

Found that with, what else, a google search.

plettner

sprkymrk wrote:

Google runs on hundreds of thousands of servers—by one estimate, in excess of 450,000—racked up in thousands of clusters in dozens of data centers around the world. It has data centers in Dublin, Ireland; in Virginia; and in California, where it just acquired the million-square-foot headquarters it had been leasing. It recently opened a new center in Atlanta, and is currently building two football-field-sized centers in The Dalles, Ore.

That is incredible! That's a massive amount of hardware. Imagine landing the contract to supply servers for Google.

"Oh, we'll just need another 10000 servers, thanks"

Pash

plettner wrote:

sprkymrk wrote:

Google runs on hundreds of thousands of servers—by one estimate, in excess of 450,000—racked up in thousands of clusters in dozens of data centers around the world. It has data centers in Dublin, Ireland; in Virginia; and in California, where it just acquired the million-square-foot headquarters it had been leasing. It recently opened a new center in Atlanta, and is currently building two football-field-sized centers in The Dalles, Ore.

That is incredible! That's a massive amount of hardware. Imagine landing the contract to supply servers for Google.

"Oh, we'll just need another 10000 servers, thanks"

I think they would probably agree to your quote as well if you could gurantee a quick installation haha

Sie

You know how servers get named things like 'Thor' and 'Zeus' (taken from my college nextwork a few years ago) I guess they dont do this here!!

People have a hard time thinking of one name let alone 45,000!