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Hello i am new to dedicated servers, and i have recently rented one. This server runs CentOS and i have a plesk parallel pannel.

There is only one ip adress configured in PLESK, but i have 2 ip adreses i can use. The two being

I have these two adresses sent to me by email, but i dont know what to do with them. I want to run 1 heavy application on my server, and 2 verry small ones. Now the thing i want to do is set the heavy app on one IP and the other 2 on the second.

Is this type of settup possible, and does this even make sence?

Or are the IP adresses used for other things. Thank you very much.

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up vote 1 down vote accepted

It makes no sense. Multiple IP make sense for example for SSL - running multiple SSL applications over the same IP is tricky for some servers - and for other server processes that sort of have no way to identify different instances wit only the domain name (like FTP actually, IIRC).

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Nice response, and that you for pointing me in a direction where the two ip-adresses actually make are used for something. I am going to use SSL connections on my server, so maybe i will use them for that. thanks. +1 and accepted answer – Saif Bechan Mar 10 '10 at 20:53
Note that yuo only need those if you have MULTIPLE ssl certificates. The problem is one of security - HTTP can have multiple sites on one IP address due to host header information in the request. SSL encrypts the request ;) So that info can not be used - dependign on web server design (and IIS had this problem at least before version 7 - not changed since). – TomTom Mar 11 '10 at 9:04

It's reasonable, if the two IPs are tied to two different physical interfaces (i.e. NICs), because then you're splitting the physical load and making sure one high-bandwidth application isn't slowing down two smaller applications.

It being a "dedicated server", however, it's almost certainly virtualized, and those two ip addresses are hosted on the same piece of physical hardware, in which case, you won't see any benefits.

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Thank you for the response, and yes, they are the same machine. So I think this setup is a no-go. +1 for the answer – Saif Bechan Mar 10 '10 at 20:51

If you want the applications to all run on the default HTTP port 80 or HTTPS port 443, and have different hostnames, and work with old or rudimentary HTTP 1.0 user agents, then having different IP addresses could make sense.

Back in the HTTP 1.0 days, user agents didn't send the Hostname: header in their requests, so a single web server with a single IP address hosting multiple virtual websites couldn't tell which virtual website the HTTP 1.0 user agent was asking for if it just did a GET / HTTP/1.0. So if you wanted to host multiple virtual websites on the same single host, you needed to assign separate IP addresses for each virtual website so that your web server could know which virtual website to serve up to the HTTP 1.0 client just by looking at which IP address the client was connecting to.

HTTP 1.0 user agents are probably pretty rare these days, but I still run across the occasional embedded HTTP client or rudimentary script that acts as a simple HTTP client that uses HTTP 1.0 for simplicity's sake.

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