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I recently got myself a domain name. I wanted to add a couple of sub-domains to it. I want to know what goes on when you create a new sub-domain. How does a router know how to resolve a sub-domain.

Some hosting providers also charge for creating them. Do they incur legitimate expenses to create and manage these or is it pure profit?

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migrated from Jul 19 '12 at 12:36

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If your domain host charges for sub domains, find a new host, that kind of service should be free. If you are not sure where to find one, check out . Their domains update in almost real-time, and they give you plenty of control. They also have guides for how to add sub domains. When you make a subdomain it will point to an IP address, this can be any public IP address, including ones that you used on other sub domains.

As for the costs to a business to add a subdomain. The cost is so small it is legally immeasurable. It is adding a few lines of text to a config file in a server somewhere. Charging for this server is a rip off, instead of charging for domain hosting as a whole.

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it would depend on who manages the dns servers. if your providers do, the presumably they would have to have separate zone files (it is better to organize things) etc. to manage your subdomains. if they delegate your domain to your own dns servers and you create your subdomains arbitrarily, then they should have no more overhead at all and have no reason to charge you more. not a legal expert so if they still charge you in that case, i am not sure if would be legal for them to do so.

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