Information about the Domain Name System.
What is DNS?
DNS is an acronym for Domain Name System or Domain Name Service. DNS is the hierarchy of the Internet. It allows Internet users to refer to websites by an easy-to-remember domain name, instead of an IP address. Essentially, when you enter a URL into your web browser, DNS is the method of translating the domain name in the URL to the IP address where the website is hosted.
A great way to look at DNS is by comparing it to a phone number. Your cell phone number is similar to an IP address. Your contact list in your phone is similar to DNS. When you want to call a person in your contact and you don’t know the number, you simply search for the person’s name in your phone. Similarly, when you or your computer don’t know the IP address of a website, a search is conducted to find the IP.
Steps for DNS Resolution
- An Internet user types the URL of a webpage into a browser. (i.e. http://www.findmyip.co) The browser checks the website against the DNS cache of the operating system.
- If the DNS information of the website is is the cache, the remaining steps are omitted. Otherwise, the broswer requests the web page from the Internet Service Provider (ISP).
- If the ISP knows the IP address of the website that has that webpage, it returns the IP address.If not, the ISP sends a DNS request to other ISP’s to see if they have the IP address of the website.
- Once the record is found, the IP address of the domain is returned to the user. The IP address and DNS information for the page is stored locally in the DNS cache.
How is DNS Useful?
Without DNS, everyone would be forced to remember the IP address of every website they want to view. While it may be possible, it is very impractical for Internet users to remember the IP address of every website they want to visit. In fact, you can actually visit a website by entering its IP address into your browser.
Want to see an example? Use the DNS Lookup Tool.
DNS, as a whole, is a collection of domain names that are mapped to IP addresses. The information is stored on special web servers called “name servers”. Name servers contain a collection of data, called records, that define the IP addresses for a specific domain.
What is Reverse DNS?
Reverse DNS, or rDNS, is the opposite of DNS. Reverse DNS translates an IP address to a domain name. Reverse DNS, however, is not always accurate. The reason for this is that many web servers are hosting several websites from the same IP address. This means that looking up a domain by an IP address may not always yield the results you were looking for.