Some web sites can be accessed by IP address, others can not... why is this?

[Kev]

Normally I would google this but I can't think of the right phrasing.

For example:

I can go to either http://64.233.161.103 or http://www.google.com/ and both work the same.

However, if I try to substitute http://www.anandtech.com with http://208.65.201.105 I get a Bad Request error page. I've seen other pages do this as well and would like to know how this is accomplished.

 

[Crusty]

Server configuration most likely, not much you can do about it.

 

[Kev]

Yeah but at work I'm working on a project where it would be helpful to know what the server configuration is. I have to set up a site that can not be accessed by IP address.

 

[spidey07]

There is this thing called a URL. This is what you request from a web server, or more specifically a URI. I'm not trying to talk down, but this is a very basic concept - you ask an application "gimme this, using this URI". In the application layer (HTTP) there are fields for host and URI, combined these are a URL, along with a lot of other stuff.

Best practice says you shouldn't accept HTTP requests with a URL of the IP only, but some sites still accept it. If you want to learn more google URL and URI and HTTP. When you're talking about IP address you're dealing with layer3, HTTP is layer 7. This is why you can run thousands of websites on a single IP address.

 

[spidey07]

dp

 

[spidey07]

Originally posted by: Kev
Yeah but at work I'm working on a project where it would be helpful to know what the server configuration is. I have to set up a site that can not be accessed by IP address.

So configure your web server to only answer to specific URL/URIs.

 

[Kev]

So in IIS I have to configure host headers to accomplish this?

 

[spidey07]

Originally posted by: Kev
So in IIS I have to configure host headers to accomplish this?

Yes. As the operator of a web server you need to understand what you are doing.

 

[Kev]

Well I'm not a network admin i'm a developer but thanks for the help

 

[spidey07]

Originally posted by: Kev
Well I'm not a network admin i'm a developer but thanks for the help

I didn't mean to be harsh, but as a developer you really should know this. Otherwise you can't properly develop.

 

[mcmilljb]

RFC 2616 FTW

It should help explain http/1.1 which talks about http URL's and why you use hostnames instead of ip address in your requests/messages.

"The use of IP addresses in URLs SHOULD be avoided whenever possible (see RFC 1900 [24])"

PS - RFC 1900 is from 1996 and talks about renumbering on the Internet/network which is why they recommend to use hostnames instead of ip's. Basically keeping software from being hardcoded to a specific ip address.

 

[alpineranger]

Besides the late binding of resources to ip addresses which is discussed, practically speaking there are web sites which share ip addresses (virtual servers). Thus the host name defines what site is served. Of course a default can be specified, but this would be a good justification for why this is done.