||Definition and Usage
||Common usage. Always shown in bold as two proper nouns (Capitalized).
Defines that part of a domain name that is delegated by ICANN, one of its
accredited registrars, a delegated country code authority or one of its
appointed registrars or agents as defined by the country code authority
policy. A Domain Name has a registered owner and the owner is both
Authoritative and Responsible for DNS information. example.com,
example.de, example.ny.us, example.co.uk and example.montreal.qc.ca are
all examples of Domain Names.
||Always shown as two simple nouns. Defines any part of a domain which
fully includes the Domain Name e.g. www.example.com is a domain
|Fully Qualified Domain Name (FQDN)
||Common Usage. Unambiguously defines a domain name to the root. A FQDN
MUST therefore include the root which in turn means it must have a final
DOT on the extreme right of the domain name e.g. www.example.com. is a
fully qualified domain name www.example.com is not (it does not terminate
with a DOT). Because of the arbitrary starting point of any domain name
this term does not specify or mandate any starting point only that it must
end with the root. There is no commonly used term that describes a
host-to-root domain name.
||Fully defines a host within a domain, for example, fred.example.com is
a host name. Note: fred in this context is only a host name
because we know it to be a host or have discovered it to be a host via
interrogation of a DNS, that is, it has an A or AAAA RR. At its face value
it could equally well be a subdomain name.
|Qualified Domain Name
||Fairly meaningless term. Defines a part of a domain name to the root.
A qualified domain name will ALWAYS include the root which in turn means
it must have a final DOT on the extreme right of the domain name e.g.
example.com. is a qualified domain name example.com is not (it does not
terminate with a DOT).
|Second Level Domain (SLD)
||Common usage in conjunction with gTLDs to describe that part of the
Domain Name uniquely registered by the Domain owner. Defines that part of
the Domain Name below the TLD in the domain hierarchy e.g. in example.com, example is the Second Level Domain. Term less useful with ccTLDs
since the registered domain name may in fact be the Third Level domain
Name e.g. example.co.uk.
||An arbitrary name that is allocated by the owner of the Domain
Name. A sub-domain name will fully include the Domain Name.
us.example.com is a valid sub-domain.
|Top Level Domain (TLD)
||Common usage. Defines the TLD part of a Domain Name (q.v.) Top
Level Domains are split into Generic Top Levels Domains (gTLDs) and
Country Code e.g. .com, .int etc. and Top Level Domains (ccTLDs) e.g. .us,
.ca, .de etc..
|Unqualified Domain Name
||Imprecise term. Common usage to describe something that is not a Fully
Qualified Domain Name (FQDN) i.e. it does not end with a dot.
||Any part of a domain that is configured in a DNS server and which
fully contains the Domain Name for which the owner is authoritative
i.e. example.com, us.example.com (a delegated sub-domain) are Zone Names.
A zone is an operational convenience for DNS software and not part of the
domain naming hierarchy. RFC 1034 describes sub-domains zones as
subzones rather than re-use the term zone and to the process of creating
sub-domains as 'cuts' in the name space. The term subzone appears to have
been lost in history.
||In an attempt to be consistent we use the term clause to
describe the top level organization in the named.conf file e.g. the zone
clause. A clause groups together related statements. What we call a
clause is variously called a section, a clause, a statement or an option
in other documents. Webster defines a clause to be "a separate section of
a discourse or writing; specifically : a distinct article in a formal
document" which is good enough for us. We also looked at the source code
and found the same terminology.
||We use the term statement to describe an item in a clause of a
named.conf file e.g. the allow-transfer statement may be used in a view,
options or zone clause. What we call a statement is variously called a
clause, a statement, an option, a substatement and a phrase in other
documents. Webster defines a statement to be "a single declaration or
remark" which is good enough for us.