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TCP/IP Network Administration

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Getting Started
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4.4 Planning Naming Service

To make your network user-friendly, you need to provide a service to convert hostnames into IP addresses. Domain name service (DNS) and the host table, explained in Chapter 3 , perform this function. You should plan to use both.

To configure her computer, a network user needs to know the domain name, her system's hostname, and the hostname and address of at least one name server. The network administrator provides this information.

4.4.1 Obtaining a Domain Name

The first item you need for domain name service is a domain name. You can obtain an official domain name from the InterNIC. Your ISP may be willing to do this for you or to assign you a name within its domain; however, it is likely that you will have to apply for a domain name yourself. You can download the application from ftp://rs.internic.net/templates/domain-template.txt .

Pre-select a domain name and have your primary domain name server up and running before you attempt to register the domain name. Use whois as described in Chapter 13, Internet Information Resources , to see if the name you want is in use. Double-check with nslookup as described in Chapter 8, Configuring DNS Name Service . When you are reasonably sure the domain name is still available, start your primary name server running. If you don't want to run your own server, ask your ISP if they offer this service. If they don't, you must either find a new ISP that does, or run the service yourself.

Having the primary server up and running doesn't mean that your entire domain must be fully operational, but it does mean that a server must be running to respond to basic queries. When asked, the server should answer that it is the name server for your domain. Configure the primary server as described in Chapter 8 . Test it with nslookup . Once you are sure that it at least answers queries about itself, register the domain name.

Submit the domain name application form via email to with a subject line containing the words "NEW DOMAIN" followed by the name of your domain. For example, assuming the completed template is stored in the file domain.application on a Solaris system, the following command might be used to mail it to the InterNIC for a domain named nuts.com :

Mail hostmaster@internic.net

NEW DOMAIN nuts.com

~r domain.application

"domain.application" 49/2732



In response to your email, you receive a reply that contains a tracking number that you use to monitor the status of your domain registration.

Use the domain name registration form to change or delete your existing domain name registration. Just fill in the form with the corrected information and mail it to with a subject line that contains either "MODIFY DOMAIN" or "REMOVE DOMAIN", as appropriate, followed by your domain name. In the very first field of the application form, item 0, ask for the type of registration action: either New ("N"), Modify ("M"), or Delete ("D"). Make sure the letter in this field matches the action indicated on the subject line when you mail in the application.

You're required to use email to submit the domain name application. The logic behind this is that if you don't have at least email access to the Internet, you don't need an Internet domain name. This helps reduce the number of frivolous domain name requests, and it automates part of the registration, further reducing the burden of handling domain name requests.

Another thing that dramatically reduces the number of frivolous domain name applications is the $100 registration fee. The registration service charges each domain $50 a year to be maintained in the registry. The initial $100 fee covers the first two years. Question 9 asks if the InterNIC should send the bill for the registration fee to you via email or postal mail. Answer with an "E" or a "P". If your "bean counters" will accept an email bill, go that way. You'll get everything finished more quickly.

The application form is largely self-explanatory, but a few items require some thought. Two things may be confusing - handles and servers. One is the request for a NIC handle . You have a NIC handle only if you are registered in the NIC white pages . The white pages (discussed in Chapter 12 ) is a directory of information about users, networks, hosts, and domains. A NIC handle is a record identifier for this directory. A personal NIC handle for a user entry is composed of the user's initials and perhaps a number. For example, my initials are cwh and my NIC handle is cwh3 . It is unlikely that you will have a handle unless you have contacted the NIC before. If you don't have a handle, just leave it blank. The NIC will assign you one.

You're also asked for the names and addresses of your primary and secondary name servers. The servers listed must be operational and connected to the Internet. [7] Provide the full domain name of the primary server in response to question 7a; e.g. almond.nuts.com . The primary server is usually a name server located at your site, but not always. It isn't necessary to provide your own primary server; and if you aren't directly connected to the Internet, you can't. Even though you are not connected, you may still want to register your domain name with the NIC if you have email access to the Internet. This allows you to use an email address that clearly identifies your organization. In order to do this, the online service that receives your email must be able to provide your primary name service. Check with them before you fill out this form.

[7] Chapter 8 tells you how to get a name server up and running.

The secondary server should be on a separate physical network from the primary server. Putting it on a different network guarantees that other sites can look up information about your network, even if access to your network is unavailable for some reason. A large organization may have multiple independent networks, but for many sites this requirement means asking another organization to provide a secondary name server. Who do you ask?

Again, you should turn to the people who are providing your Internet access. The network that connects you to the Internet should provide secondary name servers as a service to its users. If they do not, they should be able to point you to other organizations that do provide the service. It is even possible for two organizations who are both applying for new domains to provide secondary service for each other. In other words, you provide someone with a secondary server; in return, they provide a secondary server for you.

Read the instructions that come with the domain application. The remainder of the form should be easy to fill out. Obtaining an IN-ADDR.ARPA domain

When you obtain your Internet domain name, you should also apply for an in-addr.arpa domain. This special domain is sometimes called a reverse domain . Chapter 8 contains more information about how the in-addr.arpa domain is set up and used, but basically the reverse domain maps numeric IP addresses into domain names. This is the reverse of the normal process, which converts domain names to addresses. If your ISP provides your name service or your ISP assigned you an address from a block of its own addresses, you may not need to apply for an in-addr.arpa domain on your own. Check with your ISP before applying. If you do need to get a reverse domain, you can obtain the application from ftp://rs.internic.net/templates/in-addr-template.txt .

4.4.2 Choosing a Hostname

Once you have a domain name, you are responsible for assigning hostnames within that domain. You must ensure that hostnames are unique within your domain or subdomain, in the same way that host addresses must be unique within a network or subnet. But there is more to choosing a host name than just making sure the name is unique. Choosing a hostname is a surprisingly emotional issue. Many people feel very strongly about the name of their computer because they identify their computer with themselves or their work.

RFC 1178 provides excellent guidelines on how to choose a hostname. Some key suggestions from these guidelines are:

  • Use real words that are short, easy to spell, and easy to remember. The point of using hostnames instead of IP addresses is that they are easier to use. If hostnames are difficult to spell and remember, they defeat their own purpose.

  • Use theme names. For example, all hosts in a group could be named after human movements: fall, jump, hop, skip, walk, run, stagger, wiggle, stumble, trip, limp, lurch, hobble, etc. Theme names are often easier to choose than unrestricted names, and increase the sense of community among network users.

  • Avoid using project names, personal names, acronyms, numeric names, and technical jargon. Projects and users change over time. If you name a computer after the person who is currently using it or the project it is currently assigned to, you will probably have to rename the computer in the future. Use nicknames to identify the server function of a system, e.g., www , ftp , ns , etc. Nicknames can easily move between systems if the server function moves. See the description of CNAME records in Chapter 8 for information on creating nicknames.

The only requirement for a hostname is that it be unique within its domain. But a well-chosen hostname can save future work and make the user happier.

Name service is the most basic network service, and it is one service that you will certainly run on your network. There are, however, other services that you should also include in your network planning process.