6.4.3 Define Domain Server.
- A ``domain'' is a subset of the domain name space. The mynet.com and acme.com domains share the com portion of their domain name because they both lie within the com domain. Thus all domains are effectively part of the root domain.
- A ``subdomain'' or ``child domain'' is a domain that branches off another. For example, in the diagram rivers.mynet.com, seas.mynet.com and lakes.mynet.com are subdomains of mynet.com. All domains except the root domain are therefore subdomains of another domain.
- A DNS ``master name server'' is a computer that maintains host name and address databases for one or more zones. Zones usually also have ``slave'' name servers which act as backup servers should the master name server be unreachable or down.
DNS name server type
The SCO implementation of DNS supports the following server configuration types:
- ``Master name servers''
- ``Slave name servers''
- ``Stub servers''
- ``Caching-only name servers''
Master Name Servers
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| Example Of Master Name Servers |
A master name server is authoritative for one or more DNS zones. Each server maintains its data in database files, and may transfer this data periodically to a slave server if one exists in the zone.
Structure of Domain
The Internet domain structure
The Internet domain name space is divided into several organizational and geographical top-level domains. Top-level non-geographic domains include:
- COM (commercial organizations)
- EDU (educational organizations)
- GOV (government organizations)
- INT (international organizations)
- MIL (military departments)
- NET (networking organizations)
- ORG (miscellaneous organizations)
The top-level domains are shown here in upper case. In fact, domain names are case-insensitive. That is, the COM domain is equivalent to the com domain and is usually written in lower case.
Although the three-letter top-level domains are primarily intended for use by companies and organizations in the United States, domain names in COM, EDU, INT, NET, and ORG are often allocated to companies and organizations in other countries.
Geographical top-level domains generally follow the ISO 3166 standard, which contains abbreviations for each country (for example, ca for Canada, ch for Switzerland, and it for Italy). An exception is the domain uk(United Kingdom) which is used for Great Britain rather than the value gb defined by the standard.
Although the three-letter top-level domains are primarily intended for use by companies and organizations in the United States, domain names in COM, EDU, INT, NET, and ORG are often allocated to companies and organizations in other countries.
Geographical top-level domains generally follow the ISO 3166 standard, which contains abbreviations for each country (for example, ca for Canada, ch for Switzerland, and it for Italy). An exception is the domain uk(United Kingdom) which is used for Great Britain rather than the value gb defined by the standard.
A domain server is a centralized computer HostMyCode that manages network resources and user accounts within a domain, providing authentication and authorization services.
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