What is DNS
DNS is networking service and it stands for the Domain name system. On the networks and on the internet it is used to convert the host name into the IP addresses and the IP addresses into the hostname. It serves as a telephone directory for the internet by translating the numeric addresses into the human reasonable names, which are known as domain names. The list of the domain names and the IP addresses is distributed throughout the internet. On the internet, the DNS servers are interconnected with each other and if a DNS server at a local ISP does not know that how to translate a particular domain name, it sends the request to the next connected DNS and so on unless the specified domain name is translated into the IP address.
When a client’s web browser sends a request for a website, the DNS revolver (usually built in the operating systems) first contacts the DNS server of the local ISP. The DNS server at the ISP looks into it database for the specific request page and if it does not find that page the request is forward to the next adjacent DNS and so on, until the requested page is returned back to the client. Every computer on the internet require a unique IP address and a server has a static IP address that does not change very often like the DNS, FTP, Web Server, DHCP, Gateway and the internet printer’s IP addresses. The DNS name consists of two parts separated by the dots.
The right most part of the name is known as Top Level Domain TLD. Sub domains are usually the name of the organizations or the organization’s departments that owns that domain such as finance.yahoo.com, mail.yahoo.com, news.yahoo.com and entertainment.yahoo.com etc. The most common and functional domain names are the following.
TLD |
Description |
.Com |
Commercial domains |
.Net |
Usually owned by the ISPs |
.Org |
Private and non profit organizations |
.Info |
Informative websites |
.Gov |
Owned by the government institutes |
.Edu |
Owned by the educational institutes such as colleges and universities. |
In order to understand the DNS functionalities you need to know the following most commonly used terms.
DNS Terminology
Usually a name of the computer system or website
Revolver is a system process through which a compute queries a name server for the zone information.
Origin refers to the domain name in the particular zone file.
A Zone is a domain a portion of the domain or the sub domain.
Root zone is the beginning of the internet zone hierarchy. All the zones fall under the root zone.
Mapping of the hostname into the IP address.
Mapping of the IP address into the hostname.
Delegation is the distribution process of the domain name system through the internet.
MX (MailXchanger) are used to identity the name servers that are handles the specific emails.
NSlookup is a diagnostic and troubleshooting command for the DNS in the Windows based operating systems.
An A records provide the IP address of the Host.
TXT records are used to store the host information such as it’s physical location, MAC address and the user id of the person who is responsible for managing the DNS.
PTR records provide a reverse lookup that provide the name what is associated with the IP addresses.
|
