Hosting (From Home) for Fun and Profit: Prerequisites, Hardware, and Network - DNS
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In order to use a Domain Name, you need to have Domain Name Servers (DNS) that map your domain and any sub-domains that you may have to the IP address of the server hosting them. Some explanation of DNS in general may be useful in understanding how you set it up:
When a user types a domain name like www.microsoft.com into a web browser, the browser first sends out queries to the domain name system to resolve that domain name to an IP address. It starts with the DNS servers the user has defined locally and continues up the DNS tree until the browser find which servers it must consult to resolve the domain name. After the browser has resolved the domain name to an IP address, it can use the regular TCP/IP protocol to connect to the web server(s) that hosts www.microsoft.com and start transferring data. In reality, there are many details of this system that I haven’t addressed, but this works as a rough explanation.
The structure of this system dictates that there must be some DNS servers that know your domain name and can relate that domain name to your IP address. There are several different services that provide DNS service to the public. For example, Zoneedit.com will serve 5 domain names for free on their DNS servers. After you buy your domain name, its DNS will most likely be hosted on your registrar’s parking servers until you define other DNS servers for that domain. Once you find a DNS service provider that you wish to use, they will give you the names of their DNS servers that have your domain information. Some examples of what these may be are: ns15.zoneedit.com and ns16.zoneedit.com. You will also notice that you need two domain name servers, this is for redundancy in case one goes down, a user will still be able to get the domain information and find your site.
One other problem to keep in mind when setting up DNS is the time lag between when you buy a domain name and when it actually takes effect in the top level domain registry. Ususally, registrars say it may take up to 72 hours before the domain change (new DNS servers being assigned to your domain with the top level servers), however it is usually much shorter than that. Changes that you make to the DNS servers themselves becomes live immediately.
Subdomains are anything to the left of the actual domain name. For instance in www.microsoft.com, the “www” is the subdomain. You can set up many different subdomains. You can put just about anything in front of the domain name (the microsoft.com part). Some typical ones are: www, ftp or mail. If you were to host an FTP server on a different IP than the one that hosts the webserver, you are able to map that subdomain to a different IP. In most cases, with home webserving, you will not map any subdomains to more than one IP, since most residential broadband connections are not allocated more than on IP address. You will want to set up at the very least the “www” subdomain as this is what most people will use to try and access you webserver.
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