DNS resolver gives an IP that ISN'T the domain's?

I've been working on my own DNS resolver lately (for education purposes), and I just encountered a weird thing...

My resolver, and two other online resolvers (DNS <-> IP converter and Web Based DNS Lookup (NSLookup) (ZoneEdit.com)) are coming to the same conclusions (which should make be think that my resolver is working) on this.

www.google.com -> 74.125.127.104
cboard.cprogramming.com -> 76.74.255.245

But if you look at both Google links, and both C Board links, you'll see that they are in fact, not the same thing. What in the world?

What do you think is happening here?

Oh yes, and the ping utility comes to the same conclusions too.
Something else that all 4 resolvers do, is map cboard.cprogramming.com and www.cprogramming.com to the same IP.
Yet, for some reason, besides all this weirdness, my browser is able to navigate just fine! (It stinks that FF won't show you the IP of the page your at, so I could compare.)

I do not understand what you are complaining for.

if you put the google ip into the browser you get the google site, so on that ip the google web-site is really hosted...
google itself could redirect you to another ip that is closer to your location...

with the cboard - on the same ip could be hosted several domains... what is your problem with it?

The server that is hosting CProgramming is configured to support multiple domain names, therefore it doesn't show CProgramming site when you enter the IP address.

Are you wondering how the server knows which domain you are requesting even though the client resolves the domain name before sending the request? It's pretty simple actually - the domain name is included in the HTTP headers.

Quote:

---

Originally Posted by vart

with the cboard - on the same ip could be hosted several domains... what is your problem with it?

---

Yeah, you can set up apache to serve "virtual domains":

Code:

---

<VirtualHost *:80>
    ServerName dev.docsearch.net
    DocumentRoot "html/docsearch/public/"

---

I haven't tried this online, but I presume that if you had dev.docsearch.net registered to your IP, it gets directed to your server which then decides what to use as DocumentRoot.

Quote:

---

Originally Posted by maxorator

The server that is hosting CProgramming is configured to support multiple domain names, therefore it doesn't show CProgramming site when you enter the IP address.

Are you wondering how the server knows which domain you are requesting even though the client resolves the domain name before sending the request? It's pretty simple actually - the domain name is included in the HTTP headers.

---

This answers my question.
I didn't know there was such a feature - but I guess it was stupid of me not to guess to the obvious.
Thanks.

In fact google.com resolves to many different addresses. A records don't have to be a 1-to-1 mapping of hostname to IP.

I know. It seems that most resolvers just use the first one they see, I'd only be interested in the others if the first one failed to get me anywhere. (But I've not seen any browser do that, so in practicality, the other IPs are somewhat pointless.)

Not really. Having multiple IPs is a poor man's way of load balancing. Basically you get round robin DNS.

Does that mean that a 'nice' resolver should randomly choose from the list? If so, most are mean. Or will the DNS host shuffle them after a while? Or the target site's NS give a shuffled list to other nameserver?