What is a Domain Name and Domain Name System?
Domain name is a self identification label that defines a realm of administrative autonomy, authority, or control in the Internet, based on the Domain Name System (DNS). Domain names are names that uniquely identifies a website on the Internet or other TCP/IP (transmission control protocol/Internet protocol) networks and serve as user-friendly substitutes for numeric IP addresses.
Domain Name System is a hierarchical naming system for computers, services, or any resource connected to the Internet that translates names in IP addresses and vice-versa. Domain Name System serves as a "phone book" for the Internet by translating human-friendly computer hostnames into IP addresses. The domain name system is the network of programs and databases on the Internet that functions to translate domain names to IP addresses. For example,
Example Web Page translates to 208.77.188.166.
A root server is any of the small number domain name system (DNS) servers on the Internet that contain the IP addresses of the top level domain (TLD) registry organizations maintaining the global domains (e.g., .com, .org, net, .gov and .edu) and the country code domains (e.g., .uk, .ca, .cn, .dk, .fr, and .jp).
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1. A
Top level domain (TLD) in the domain name system (DNS) is the highest level of the hierarchy after the root servers. Top-level domains (TLDs) are first-level set of domain names those include the generic top-level domains (gTLDs), such as the prominent domains .com, .net and .org, and the country code top-level domains (ccTLDs). In a domain name, the TLD is the last part of the name, that is, the segment after the final dot and furthest to the right. For example, it is the com in yourdomain.com. There are approximately 300 TLDs on the Internet. Each consists of at least two alphabetic characters. The most common by far is .com.
TLDs are classified into two main groups: generic (gTLD) and country codes (ccTLD).
a) The former, which are the most frequently used, each consist of at least three alphabetic characters. They include names such as .com (commercial), .net (network), .org (organization), .gov (government), .edu (education) and .mil (military). Most gTLDs are available for use worldwide, but for historical reasons .gov and .mil are restricted to the U.S. government and U.S. military. The number is occasionally increased.
b) The great bulk of TLDs are country codes. These consist of two letters that represent individual countries. Examples include .au (Australia), .br (Brazil), .ca (Canada), .cn (China), .fr (France) .ie (Ireland), .it (Italy), .jp (Japan), .th (Thailand). .uk (United Kingdom), .us (United States) and .za (South Africa).
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2. A
Second-level domain is the portion of a domain name directly below the top level domain (TLD) in the domain name system (DNS) hierarchy and the portion that appears immediately to the left of the TLD. Second-level domain names provide the name of the organization and/or are descriptive of the service that it provides. A second-level domain is the portion of a Uniform Resource Locator (URL) that identifies the specific and unique administrative owner associated with an Internet Protocol address (IP address).
For example, the wikipedia in
Wikipedia
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3. A
Third-level domain is the next highest level in the domain name system hierarchy below the second level domain and the segment that appears directly to the left of the second level domain. For example, the www in
Wikipedia is a third-level domain. .org is a top level domain and wikipedia is a second-level domain. The www would still be the third-level domain even if it were the fourth segment of the domain name because of the addition of a ccTLD, for example
www.wikipedia.org.us.
The third level domain is typically used to refer to a specific server within an organization. In larger organizations each division or department might have its own third level domain, which can serve as an effective means for identifying it. www is the default third-level domain name and the most common by far. You can use a third-level domain name, such as "support.domain.com." where the " www " is replaced by " support ". Typically a third-level domain name is used to refer to different servers within different departments of a company.
Third-level domains are also known as subdomains and CNAMEs. In a URL, the subdomain is written before the domain name. Here's some examples:
Subdomain URL
affiliates --------
Art.com Affiliate Program
www -------------
Home - Rockefeller Foundation
men --------------
http://men.style.com]GQ.COM - GQ.com
mail -------------
http://mail.google.com
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4. A
Fourth-level domain is the next highest level in the domain name system hierarchy below the third level domain and the segment that appears directly to the left of the third level domain. For Example,
the www in
Web Hosting UK | Dedicated Servers | VPS Web Hosting is a fourth-level domain. .com is a top level domain, .uk is a second-level domain, webhosting is a third level domain. The www is the fourth-level domain.
Note : In the Third Level Domain, there's a difference in the country extension as mentioned above. In third-level domain, the country code is at the last and in the fourth level domain, the country code is before the generic top-level domain name.
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5. The
Fifth-level domain is the highest and last level in the domain name system hierarchy below the foruth level domain and the segment that appears directly to the left of the fourth level domain. For Example, the www in
Web Hosting UK - 24x7 Helpdesk | Toll Free Phone Support | LiveChat Support is a fifth-level domain. .com is a top level domain, .uk is a second-level domain, webhosting is a third level domain, support is a fourth-level domain. The www is the fifth-level domain name.
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IMPORTANT : The whole Domain Name can not exceed a total length of 255 characters, however some registries have shorter limits.
I hope this should have cleared all the levels of domain names in a Domain Name System hierarchy..
Domain Name | Domain Name System
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