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3.2 Choosing a Domain Name
Choosing a
domain name is more
involved than it may sound because it entails both choosing a name
and finding out who runs the parent zone. In
other words, you need to find out where you fit in the Internet
domain namespace, then find out who runs that particular corner of
the namespace.The first step in picking a domain name is finding where in the
existing domain namespace you belong. It's easiest
to start at the top and work your way down: decide which top-level
domain you belong in, then which of that top-level
domain's subdomains you fit into.Note that in order to find out what the Internet domain namespace
looks like (beyond what we've already told you),
you'll need access to the Internet. You
don't need access to a host that already has name
service configured, but it would help a little. If you
don't have access to a host with DNS configured,
you'll have to
"borrow" name service from other
name servers (as in our previous
ftp.microsoft.com example) to get you going.
3.2.1 On Registrars and Registries
Before we go any further, we need to define a few
terms:
registry,
registrar, and registration. These terms aren't
defined anywhere in the DNS specs. Instead, they apply to the way the
Internet namespace is managed today.A registry is an
organization responsible for maintaining a top-level
domain's (well, zone's, really)
datafiles, which contain the delegation to each subdomain of that
top-level domain. Under the current structure of the Internet, a
given top-level domain can have no more than one registry.A registrar acts as
an interface
between customers and the registry, providing registration and
value-added services. It submits to the registry the zone data and
other data (including contact information) for each of its customers
in a single top-level
domain.Registration
is the process by which a customer tells a
registrar which name servers to delegate a subdomain to and provides
the registrar with contact and billing information. The registrar
makes these changes through the registry.To give you some concrete examples of how this works in the real
world, Public Interest Registry runs the
org registry. VeriSign, Inc. currently acts
as the registry for the com and
net top-level domains. There are dozens of
registrars for com, net,
and org, including Network Solutionsa former
subsidiary of VeriSign. An organization called
EDUCAUSE runs the
edu registry and is its only registrar. But
before we get too off-track, let's get back to our
story.
3.2.2 Where in the World Do I Fit?
If
your organization is attached to the Internet outside of the United
States, you first need to decide whether you'd
rather request a subdomain of one of the generic top-level domains,
such as com, net, and
org, or a subdomain of your
country's top-level domain. The generic top-level
domains aren't exclusively for U.S. organizations.
If your company is a multi- or transnational company that
doesn't fit in any one country's
top-level domain, or if you'd simply prefer a
generic top-level to your country's top-level
domain, you're welcome to register in one. If you
choose this route, skip to "The generic top-level
domains" later in this chapter.If you opt for a subdomain under your country's top
level, you should check whether your country's
top-level domain is registered and, if it is, what kind of structure
it has. Consult our list of the current top-level domains (Appendix
C) if you're not sure what the name of your
country's top-level domain would be.Some countries' top-level domains, such as New
Zealand's nz,
Australia's au, and the United
Kingdom's uk, are divided
organizationally into second-level domains. The names of their
second-level domains, such as co or
com for commercial entities, reflect
organizational affiliation. Others, like France's
fr domain and Denmark's
dk domain, are divided into a multitude of
subdomains managed by individual universities and companies, such as
the University of St. Etienne's domain,
univ-st-etienne.fr, and the Danish Unix Users
Group's dkuug.dk. Many
top-level domains have their own web sites that describe their
structure. If you're not sure of the URL for your
country's top-level domain's web
site, start at http://www.allwhois.com, a directory of links to such web sites.If your country's top-level domain
doesn't have a web site explaining how
it's organized, but you have some idea of which
subdomain you belong in, you can use a DNS query tool such as
nslookup to find the email address of the
technical contact for the subdomain. (If you're
uncomfortable with our rushing headlong into
nslookup without giving it a proper
introduction, you might want to skim Chapter 12.)To find out whom to ask about a
particular subdomain, you'll have to look up the
corresponding zone's
start of authority (SOA) record. In
each zone's SOA record, there's a
field that contains the electronic mail address of the
zone's technical contact.[2] (The other fields in the
SOA record provide general
information about the zonewe'll discuss them
in more detail later.)[2] The
subdomain and the zone have the same domain name, but the SOA record
really belongs to the zone, not the subdomain. The person at the
zone's technical contact email address may not
manage the whole subdomain (there may be additional delegated
subdomains beneath), but he should certainly know the purpose of the
subdomain.
For example, if you're curious about the purpose of
the csiro.au subdomain, you can find out who
runs it by looking up
csiro.au's SOA record:
C:\> nslookup - 207.69.188.185
Default Server: ns1.mindspring.com
Address: 207.69.188.185
> set type=soa Look for start of authority data
> csiro.au. for csiro.au.
Server: ns1.mindspring.com
Address: 207.69.188.185
csiro.au
origin = zas.csiro.au
mail addr = hostmaster.csiro.au
serial = 2003071501
refresh = 10800 (3H)
retry = 3600 (1H)
expire = 3600000 (5w6d16h)
minimum ttl = 3600 (1H)
The
mail addr field is the Internet address of
csiro.au's contact. To convert
the address into Internet email address format,
you'll need to change the first
"." in the address to an
"@". So
hostmaster.csiro.au becomes
hostmaster@csiro.au.[3][3] This form of Internet mail address is a
vestige of two former DNS records, MB and MG. MB (mailbox) and MG
(mail group) were to be DNS records specifying Internet mailboxes and
mail groups (mailing lists) as subdomains of the appropriate domain.
MB and MG never took off, but the address format they would have
dictated is used in the SOA record, maybe for sentimental
reasons.
3.2.2.1 whois
The
whois
service can also help you figure out
the purpose of a given domain. Unfortunately, there are many
whois serversmost good administrators of
top-level domains run oneand they don't talk
to each other, like name servers do. Consequently, the first step to
using whois is finding the right
whois server.One of
the easiest places to start your search for the right
whois server is at http://www.allwhois.com (see Figure 3-1). We mentioned earlier that this site has a
list of the web sites for each country code's
top-level domain; it also sports a
unified whois
search facility.
Figure 3-1. The www.allwhois.com web site
Say you were wondering what the ad.jp domain was
for. You can enter ad.jp in the text box at the
top of http://www.allwhois.com/
and the web site will query the right whois
server and show you the results, as in Figure 3-2.
Figure 3-2. Information about ad.jp from the jp whois server
Obviously, this is a useful web site if you're
looking for information about a domain outside of the
U.S.Once you've found the right web site or the right
contact, you may have found the registrar. Outside the U.S., many
domains have a single registrar. A few, though, such as
Denmark's dk and Great
Britain's co.uk and
org.uk, have multiple registrars. However, the
process we've described will still lead you to them.
3.2.3 Back in the U.S.A.
In true cosmopolitan spirit, we covered international domains first.
But what if you're from the good
ol' U.S. of A.?If you're in the U.S.,
where you belong depends mainly upon what your organization does, how
you'd like your domain names to look, and how much
you're willing to pay. If your organization falls
into one of the following categories, you may want to consider
joining us:K-12 (kindergarten through twelfth grade) schoolsCommunity colleges and technical vocational schoolsState and local government agencies
That's because these organizations have historically
registered under us, according to the namespace
design documented in RFC 1480. In that design, a high school, for
example, would register under
k12.<state>.us, where
<state> is the two-letter postal
abbreviation for the state in which the school is located.However, even these organizations don't need to
follow this rigid structure. Many K-12 schools, community colleges,
and government agencies register subdomains of
org or even com. The
registry that runs us has relaxed the
restrictions placed on us registrants, too: now
you can register in either the "locality
space" (<state>.us) or
the "expanded space." In the
"expanded space," you could
register (for example) acme.us rather than
acme.co.us.Many people, however, prefer the better-known generic top-level
domains. For information on registering in one of those, read on.
3.2.3.1 The generic top-level domains
As we said, there are many reasons why
you might want to ask for a subdomain of one of the
generic top-level domains, such as
com, net, and
org: you work for a multi- or transnational
company, you like the fact that they're
better-known, or you just prefer the sound of your domain name with
"com" on the end.
Let's go through a short example of choosing a
domain name under a generic top-level domain.Imagine you're the network administrator for a think
tank in Hopkins, Minnesota. You've just gotten a
connection to the Internet through a commercial ISP. Your company has
never had so much as a dialup link, so you're not
currently registered in the Internet namespace.Since you're in the United States, you have the
choice of joining either us or one of the
generic top-level domains. Your think tank is world-renowned, though,
so you feel us wouldn't be a
good choice. A subdomain of a generic top-level domain would be best.But which one? As of this writing, there are five open to anyone:biz
A new generic top-level domain
com
The original generic top-level domain, and the best known
info
A new generic top-level domain
net
Originally used by networking organizations, but now open to anyone
org
Originally used by nonprofit and other noncommercial organizations,
but now open to anyone
The think tank is known as The Gizmonic Institute, so you decide
gizmonics.com might be an appropriate domain
name. Now you've got to check whether the name
gizmonics.com has been taken by anyone, so you
use an account you have at the University of Minnesota:
C:\> nslookup
Default Server: ns.unet.umn.edu
Address: 128.101.101.101
> set type=any Look for any records
> gizmonics.com. for gizmonics.com.
Server: ns.unet.umn.edu
Address: 128.101.101.101
gizmonics.com nameserver = ns1.11l.net
gizmonics.com nameserver = ns2.11l.net
Whoops! Look like gizmonics.com is already taken
(who would have thought?). Well,
gizmonic-institute.com is a little longer, but
still intuitive:[4][4] If you're having a
hard time figuring out a good domain name, many
registrars' web sites provide suggestions for free.
For example, "institute," even using rhyming
words.
C:\> nslookup
Default Server: ns.unet.umn.edu
Address: 128.101.101.101
> set type=any Look for any records
> gizmonic-institute.com. for gizmonic-institute.com.
Server: ns.unet.umn.edu
Address: 128.101.101.101
*** ns.unet.umn.edu can't find gizmonic-institute.com.: Non-existent host/domain
gizmonic-institute.com is free, so you can go on
to the next step: picking a registrar.
3.2.3.2 Choosing a registrar
Choose a registrar? Welcome to the brave
new
world of competition! Before the spring of 1999, a single company,
Network Solutions, Inc., was both the
registry and sole registrar for com,
net, and org, as well as
edu. To register a subdomain of any of these
generic top-level domains, you had to go to Network Solutions.In June 1999, ICANN, the organization that manages the domain
namespace (we mentioned them in the last chapter) introduced
competition to the registrar function of com,
net, and org. There are now
dozens of com, net, and
org registrars from which you can choose (see
http://www.internic.net/registl).We won't presume to tell you how to pick a
registrar, but take a look at the price and any other services the
registrar provides that interest you. See if you can get a nice
package deal on registration and aluminum siding, for example.
3.2.4 Checking That Your Network Is Registered
Before proceeding, you
should check
whether
or not your IP network or networks are registered. Some registrars
won't delegate a subdomain to name servers on
unregistered networks, and network registries (we'll
talk about them shortly) won't delegate an
in-addr.arpa zone that corresponds to an
unregistered network.An IP network defines a range of IP addresses. For example, the
network 15/8 is made up of all IP addresses in the range 15.0.0.0 to
15.255.255.255. The network 199.10.25/24 starts at 199.10.25.0 and
ends at 199.10.25.255.
once the official source of all IP networks; they assigned all IP
networks to Internet-connected networks and made sure no two address
ranges overlapped. Nowadays, the InterNIC's old role
has been largely assumed by Internet service
providers (ISPs), who allocate space from their own networks for
customers to use. If you know your network came from your ISP, the
larger network from which your network was carved is probably
registered (to your ISP). You may still want to double-check that
your ISP took care of registering their network, but you
don't have to (and probably can't)
do anything yourself, except nag your ISP if they
didn't register their network. Once
you've verified their registration, you can skip the
rest of this section and move on.
|
are an ISP, you should check to see whether your
network is registered. Where do you go to check whether your network
is registered? Why, to the same organizations that register networks,
of course. These organizations, called regional Internet
registries,
or RIRs, each handle network registration in
some part of the world. In North America, ARIN, the American Registry of
Internet Numbers (http://www.arin.net),
hands out IP address space and registers networks. In
Asia and the Pacific, APNIC, the Asia Pacific Network
Information Center (http://www.apnic.net),
serves the same function. In Europe,
it's the RIPE Network Coordination
Centre (http://www.ripe.net).
And Latin America and the Caribbean are served by
LACNIC, the Latin America and Caribbean Internet Addresses Registry
(http://www.lacnic.net). Each RIR
may also delegate registration authority for a region; for example,
ARIN delegates registration authority for Mexico to a registry in
that country. Be sure to check for a network registry local to your
country.If you're not sure
your network is registered, the best way to find out is to use the
whois services provided by the various network
registries to look for your network. Here are the URLs for each
registry's whois web page:ARIN
http://www.arin.net/whois/indexl
APNIC
http://www.apnic.net/search/indexl
RIPE
http://www.ripe.net/perl/whois/
LACNIC
http://lacnic.net/cgi-bin/lacnic/whois?lg=EN
If you find out your network isn't registered,
you'll need to get it registered before setting up
your in-addr.arpa zones. Each registry has a
different process for registering networks, but most involve money
changing hands (from your hands to theirs, unfortunately).You may find out that your network is already assigned to your ISP.
If this is the case, you don't need to register
independently with the RIR.Once all your Internet-connected hosts are on registered networks,
you can register your zones.
3.2.5 Registering Your Zones
Different
registrars have different
registration
policies and procedures, but most, at this point, handle registration
online, through their web sites. Since you found or chose your
registrar earlier in the chapter, we'll assume you
know which web site to use.The registrar will need to know the domain names and addresses of
your name servers and enough information about you to send you a bill
or charge your credit card. If you're not connected
to the Internet, give them the IP addresses of the Internet hosts
that will act as your name servers. Some registrars also require that
you already have operational name servers for your zone. (Those that
don't may ask for an estimate of when the name
servers will be fully operational.) If that's the
case with your registrar, skip ahead to Chapter 4
and set up your name servers. Then contact your registrar with the
requisite information.Most registrars will also ask for some information about your
organization, including an administrative contact and a technical
contact for your zone (who can be the same person). If your contacts
aren't already registered in the
registrar's
whois
database, you'll also need to provide information to
register them in whois. This includes their
names, surface mail addresses, phone numbers, and electronic mail
addresses. If they are already registered in
whois, just specify their
whois
"handles" (unique alphanumeric IDs)
in the registration. There's one more aspect
of registering a new zone that we should mention: cost. Most
registrars are commercial enterprises and charge money for
registering domain names. Network Solutions, the original registrar
for com, net, and
org, charges $35 per year to register subdomains
under the generic top-level domains. (If you've
already registered a subdomain under com,
net, or org and
haven't received a bill recently,
it'd be a good idea to check your contact
information with whois to make sure
they've got a current address and phone number for
you.)If you're directly connected to the Internet, you
should also have the in-addr.arpa zones
corresponding to your IP networks delegated to you. (For information
on IPv6 reverse-mapping, see Chapter 11.) For
example, if your company was allocated the network 192.201.44/24, you
should manage the 44.201.192.in-addr.arpa zone.
This will let you control the IP address-to-name mappings for hosts
on your network. Chapter 4 also explains how to
set up your in-addr.arpa
zones.
Earlier in this chapter, we asked you to find the answers to several
questions: is your network a slice of an ISP's
network? Is your network, or the ISP network that your network is
part of, registered? If so, with which RIR? You'll
need these answers to have your in-addr.arpa
zones delegated to you.If your network is part of a larger network registered to an ISP, you
should contact the ISP to have the appropriate subdomains of their
in-addr.arpa zone delegated to you. Each ISP
uses a different process for setting up
in-addr.arpa delegation. Your
ISP's web page is a good place to research that
process. If you can't find the information there,
try looking up the SOA record for the
in-addr.arpa zone that corresponds to your
ISP's network. For example, if your network is part
of UUNET's 153.35/16 network, you could look up the
SOA record of 35.153.in-addr.arpa to find the
email address of the technical contact for the zone.If your network is registered directly with one of the regional
Internet registries, contact them to get your
in-addr.arpa zone registered. Each network
registry makes information on its delegation process available on its
web
site.Now that you've registered your zones,
you'd better take some time to get your house in
order. You've got some name servers to set up, and in
the next chapter, we'll show you how.
