Domain Naming Service (DNS) - is a distributed database of Domain Names and their corresponding IP Addresses. DNS makes it possible to attach hard to remember IP addresses to easy to remember domain names

DNS translates between meaningful host names and IP addresses. It is a hierarchical naming system used to give each server on the Internet a unique name.

DNS keeps a complete listing of all FQDNs (Fully qualified domain names) and their associated IP address.

The second name from the right is the company's or organization's unique name as registered with the Internet domain registration authority.

Any other names, except the last name (farthest left), are subdomains. Subdomains and are determined by the individual organizations.

Host Name Resolution- Host names can be mapped to IP addresses

In IP networks, host names are translated into IP addresses on the Internet by either Domain Name System (DNS) or a host table. DNS is a service used to resolve domain names to addresses on the Internet. A host table is a network directory containing a list, in ASCII file format, of commonly accessed names and addresses. Each node has its own host table from which network host and service addresses are resolved to names.

HOSTS FILES - A text file that can be edited to manually map the host name to an IP address.
DNS SERVER - A database of name/address mapping stored on a computer as is done with WINS.
LOCAL HOST NAME - Unless configured otherwise, the default name is the host name of the computer.

Host Name Resolution with DNS - DNS is a database. Like a HOSTS file, it lists host names and the IP addresses for each host. However, the DNS database is superior to the HOSTS file in two ways; it's distributed, which means many different servers can each store and maintain a small piece of the database, and it's hierarchical, which means that there can be many different levels of names.

A DNS zone is a section of the DNS database that contains domains. Representing a logical portion of the Internet, a zone expands downward in a DNS hierarchical tree until it reaches either another domain or an end node. Although a zone represents a logical Internet section, it does not have to correspond to physical Internet segments. For example, a domain can include multiple networks, or one network can span several domains.

Roles of a nameserver
Primary Nameserver- Gathers DNS information from local files and is a focal point for adding hosts and domains.
Secondary Nameserver - Gathers the data for its' zones from another DNS server, provide redundancy, traffic on primary server and quicker access for locations that are remote in regards to the primary server.
Caching only servers - do not have a zone that they are responsible for, only contain info that is received from resolutions that it has made since the the server was last started.

generic Top-Level Domains
Names that end in .com, .org, or .net are generic Top-Level Domains (gTLD) because they are available for use across the globe. Top-Level Domains (TLD)-Servers

ICANN oversees the domain name registration process
Private companies under license from ICANN

Country Code Top Level Domains - ccTLDs are two letter codes at the end of a URL that stand for a country or location. Some of the country codes are available to anyone in the world, while other codes have severe restrictions.
Countries - ccTLDs - Managed by individual countries.
US - Maintained by USC-Information Sciences Institute http://www.nic.us/

GOV - Maintained by GSA. http://www.nic.gov/
MIL - Maintained by DOD Network Information Center. http://www.nic.mil/

Windows Internet Name Service, or WINS, which automatically and dynamically builds and maintains a database that maps NetBIOS names to IP addresses.

WINS is to NetBIOS names as DNS is to host names, but it performs its functions a little differently than DNS.

The LMHOSTS file is used to resolve network addresses to NetBIOS node names (the computer name) on Microsoft-based systems. The file is found in the C:\Windows directory. This is a static file that must be manually updated. It maps NetBIOS names to the corresponding IP address. This name resolution method has been replaced by WINS.

NetBIOS Name Resolution - Applications written to the NetBIOS interface, which tend to be applications or services that were native to the Microsoft environment prior to Windows 2000, use NetBIOS names. That's because the original naming scheme in Microsoft networking was built on NetBIOS naming; host naming is native now to Windows 2000, which is built to rely entirely on TCP/IP.

Resolver is another name for a DNS client that submits requests for IP addresses. The resolver sends the request to a local domain server, which checks its database. If the server cannot find an address within its domain, it forwards the request outside the domain to a root name server.

For more information on Networking Basics, the OSI Model and Server Administration:
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