Master your domain with Linux

David M Williams
Tuesday, 09 October 2007 21:15

Business IT - Open Source

The dirt on domain names

There’s three parts to making a domain go live. First, a domain registrar provides the domain name. This is accompanied by a registry key which serves the exact same purpose as a password on a login. The registry key lets you come back and make changes to the domain name details – which include the name and address of authorised contacts as well as the DNS servers that provide detail on the domain. You can also check up on your domain’s expiry date here. But beyond these few details, that’s all the domain registrar actually stores.

If you don’t know your registry key, look for it. Make sure you know when your domain has to be renewed. And be sure to keep your on-file e-mail address up-to-date.

The third part is the physical, online, server or servers that provide your Internet presence. These may be on your premises or they may be hosted by someone else. Regardless, they will have an Internet-accessible IP address.
Many people recognise they need these first and third parts when they set up a domain. However, there’s a middle tier, and it’s the least understood.

The middle tier is the DNS servers. I’ve bandied about the term “DNS” repeatedly; it stands for “Domain Name System” and is the glue which actually ties your domain name to your mail and web services as well as any other facilities you may wish to provide (like remote access.) There are a variety of different records available, but three are particularly important.

The first is A records. An A record is an actual physical host. When you create an A record, you link both a name (e.g. “rtp-inbound-a.cisco.com”) and an IP address (e.g. “64.102.255.45”).

Next comes CNAME records. CNAME lets you make an alias for an existing host. A common example might be that you have the one physical server providing both your mail and web facilities. You thus could make an A record for, say, server.domain.com with the actual IP address. You then make CNAME records to redirect both http://www.domain.com/ and mail.domain.com to server.domain.com. If you move your host, you can just edit the one record for server.domain.com and everything continues to work.

The third important record type is MX. This stands for “mail exchanger” and identifies the host that handles mail for your domain. You might have more than one MX server, providing redundancy in case your main server is down for maintenance or any other reason.

If you don’t know who’s handling your DNS, find out. Check what the fees are. And be sure to find out if this is the best option for you. Maybe you have an alternative at no extra cost, bundled with something else you’re already paying for.

Earlier, I referred to companies who had business-grade Internet but paid someone else to manage their DNS. In Australia, the largest telco is Telstra. Customers of their Internet Direct service get free DNS hosting which can be so easily maintained via an online facility called CustData. To use it, you simply log in and set up your records. Go back to your domain registrar and set your DNS servers to be ns0.telstra.net and ns1.telstra.net. All done. You can then freely update your DNS records whenever you wish. I’d expect most major telcos and ISPs to have similar offerings.

(Oddly enough, Telstra is actually the company who also provide the managed name service on their ordinary residential BigPond Internet accounts, where you can add e-mail addresses but can’t specify a web server.)

You might also choose to use a free DNS server like ZoneEdit. This is a terrific facility with a lot of options. It’s stable and reliable. However, if your Internet presence is critical then it’s well worth paying a bit extra for an additional nameserver or for backup mail service.

When you understand DNS and where it fits in to the equation you can begin doing clever things.