17 DNS - Domain Name Service
Every computer that is connected to the Internet has a unique IP address, much like a telephone number. An IP address consists of four numbers, each of which can range from 0 to 254, separated by dots.
With a BLUEHILL.com NT Advantage Plus or BLUEHILL.com NT Advantage Pro, you actually get a 100% NT-based webserver, with its own unique IP address.
17.1 An Introduction to DNS and Name Servers
While it is possible for Internet clients to access a server by using its IP address, remembering a long number for each of your favorite sites can be difficult, if not impossible. That’s why Domain Name Service (DNS) is so useful. Domain Name Service is in the business of broadcasting more “friendly” names across the Internet, which point to corresponding IP addresses. With DNS, anyone can simply type in a domain name, which gets resolved, or translated, to the numeric IP address of a computer. With some Web browsers, for example, you can see a domain resolution happen in the status bar at the bottom of the browser window. When you type in a Web address, such as http://www.4domains.com/, the status bar of your browser may say:
Connecting to site 128.121.178.25...
Web site found, waiting for reply...
Your computer was able to match the IP address of the BLUEHILL.com machine, which is 128.121.178.25, to the domain name you entered. In order to do this, your computer needed to have some sort of reference, where it could look up domain names and match them to their corresponding IP addresses – in the same manner that you would use a phone book to look up someone’s name to get their telephone number. The Internet’s version of this “electronic phone book” is called a Domain Name Server, and is commonly referred to as simply a Name Server. When you initially set up your computer to connect to the Internet, you were required to give it at least one name server so it would know where to look up the IP addresses of the domain names you access. Most people use two name servers, called primary and secondary name servers, so that there is a backup in the event of a failure. In the above example, you could have simply typed in the IP address of the server and the connection would have been made without needing to consult a name server. However, most people on the Internet rely heavily on DNS, so that they don’t have to worry about keeping track of all those IP addresses.
A name server’s only function is to maintain a table of domain names and matching IP addresses, called a DNS Table. Each domain name on the Internet has specific DNS servers that are responsible for keeping their information in their table, and that DNS server is then responsible for broadcasting that information across the Internet. Most likely, you chose a domain name for your NT server when you first signed up. But even if you didn’t choose one, you’ve already been assigned a temporary domain name of username.BLUEHILL.com. In either case, your domain already has an entry in the DNS tables of our name servers, and this entry is an important part of what makes it possible for people to access your NT server on the Internet.
17.1.1 DNS Registration Records
There is a bit more involved in matching a domain name to an IP address than just having this information in a DNS table on a name server. Since there may be times when you want to add a domain name to your BLUEHILL.com NT Solution, or change the way your existing domain name is handled, it is important to have some understanding of how DNS works.
There are organizations responsible for distributing domain names for those who wish to use them. Many countries have their own organization, often called an NIC agency. For most U.S. domain names, including those ending in .com, .edu, and .org, this organization is called InterNIC. InterNIC is currently operated by a company called Network Solutions, and is headquartered in Herndon, Virginia.
In order to use a specific domain name with your BLUEHILL.com NT Solution, you must first register the domain name with the NIC agency responsible for that domain. The registration process differs slightly depending on the NIC agency. The registration process for U.S. domains is detailed in the next section of this guide. A domain name registration shows contact, technical, and billing information for the domain, and defines a specific name server (or group of name servers) that will contain the information on where that domain name should point. The name servers that appear in a domain’s registration record are called authoritative, because they contain the most current and correct name server information about the domain. For example, the domain registration for BLUEHILL.com looks like this:
Registrant:
Blueberry Hill Communications (BLUEHILL-DOM)
P.O. Box 11274
Palm Desert, CA 92255
US
Domain Name: BLUEHILL.com
Administrative Contact:
Campbell, Craige (CC435) cgc@BLUEHILL.com
760 469-4840 (FAX) 866-846-3559
Technical Contact, Zone Contact:
BLUEHILL.com HOSTMASTER (HC391-ORG) hostmaster@BLUEHILL.com
760-469-4840
Fax- 866-846-3559
Billing Contact:
Campbell, Craige (CC435) cgc@BLUEHILL.com
760 469-4840 (FAX) 866-846-3559
Record last updated on 25-Mar-99.
Record created on 08-Jul-95.
Database last updated on 1-Jul-99 09:00:56 EDT.
Domain servers in listed order:
NS1.VIRTSERV.COM 192.41.1.17
NS2.PERMA.NET 192.41.2.17
You can see from this record that the Registrant, or the organization that owns the domain, is Blueberry Hill Communications. The Administrative Contact, who is in charge of how this domain name is managed, is listed as “Campbell, Craige.” The Technical Contact, who is in charge of managing the technical aspects of this domain, is listed as “BLUEHILL.com HOSTMASTER.”
A domain registration record also shows the name servers that are authoritative for the IP addresses that the domain should point to. The two name servers in this record are ns1.virtserv.com and ns2.perma.net.
You can view the domain registration record for any existing U.S. domain name by typing the following from a command prompt:
The domain should be the name of the domain name whose registration you wish to view, including the domain name extension (such as .com).
Registration information such as this is kept by the NIC agencies responsible for different types of domain names all over the world. It is important to note that domain registration records do not contain the IP address(es) where a domain name should point, but merely the name and IP address of the name servers that contain this information.
17.1.2 Zone Files
Once an NIC agency has a domain name registered and has information about which name servers are authoritative for a domain, the authoritative name servers need to have the information about the IP addresses that correspond to the domain loaded into its DNS tables. This information is called a DNS Record, or zone file.
Although you will never be required to edit a DNS record directly, you may be interested in seeing what one looks like. The following is a sample DNS record, showing the IP addresse associated with your NT server, as well as the IP address for your statistics server:
;
; Nameservers
;
IN NS ns1.4servers.com. ; 168.143.168.1
IN NS ns2.4servers.com. ; 168.143.171.129
;
;
; Domain Mail Handlers
;
yourdomain.com. IN MX 0 mail
yourdomain.com. IN MX 10 mail
;
;
; Hosts in order
;
yourdomain.com. IN A Your.IP.XXX
www IN A Your.IP.XXX
mail IN A Your.IP.XXX
smtp IN A Your.IP.XXX
The first two lines show that two name servers are responsible for being authoritative. Please note that the information you enter into the name tables of the authoritative name server is not necessarily immediately available to your provider’s name servers. Because your local provider controls how often they update the name tables on their name servers, these changes may not show for several hours, or even several days. Even if a domain name is properly registered with your NIC agency, it may take your Internet provider some time to receive that new information and to store it in their DNS tables.
The third and fourth lines are called the MX records, and tells all mail coming to yourdomain.com to point to your mail server.
The remaining lines contain A records and cnames (short for canonical names). You can think of these as prefixes that can be used with your domain name, such as www.yourdomain.com, ftp.yourdomain.com or mail.yourdomain.com.
Although not shown in this DNS record, it is possible to point each cname to a different machine. The @ symbol says to associate a particular cname to the IP address above it. The IP address given for the www canonical is the address of the NT Web server.
When used in conjunction with Virtual Hosting, a cname can point to a specific directory of your NT Web server. For more on this, please see Canonical Domain Names as Virtual Hosts.
17.2 Checking the Availability of a Domain Name
The first step in registering a domain name is to check whether or not the desired domain name is still available. You can do so by visiting BLUEHILL.com's Domain Name Service at the following URL:
If the domain name is available, you can simply follow the onscreen instructions for our registration and parking service.
17.2.3 Transferring a Domain Name
To have your domain name point to BLUEHILL.com instead of your previous server, you need to modify your domain name record. To do so, you will need to contact your registrar. Most registrars have a web based interface to change this information. Because this differs from registrar to registrar, this will not be covered in this guide.
17.3 International Domain Registries
It is possible to register international domain names and use them with your virtual server. To do so goto http://4domains.com/cctlds.html
- Locate the domain registry of the country domain that you are interested in registering.
- Make sure that your domain use our name servers so that our DNS servers can handle all the DNS work for your NT server. Here is the Name Server information you will need for this option:
Primary Name Server
Primary Server Hostname....: ns1.4servers.com
Primary Server Netaddress..: 168.143.168.1
Secondary Name Server
Secondary Server Hostname..: ns2.4servers.com
Secondary Server Netaddress: 168.143.171.129
