Verrex Domain Names Web Design Web Hosting Logo Design Contact Us  
Domain Name Registration Domain Name Management Domain Name - F.A.Q Domain Terminology
   
 

Domain Name Terminology

Term Definition and Usage
Domain Name 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.
Domain Name 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 name.
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.
Host 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.
Sub-Domain Name 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.
Zone Name 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.
Clause 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.
Statement 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.