DNS Lookup

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Use the DNS lookup tool to find the IP address of a certain domain name. The results will include the IP addresses in the DNS records received from the name servers.

How DNS Works

The Domain Name System, otherwise known as DNS, is a key component of the Internet. DNS is the resolution of a domain name to an IP address. For those of you who are not aware of how it works, read on to learn the basics.

DNS Lookups

There are two approaches to DNS lookups:

  1. The "normal" or forward DNS lookup command, and
  2. The reverse DNS lookup command

Forward DNS Lookups

The forward lookup, or simple DNS lookup, is the most commonly used approach to DNS. The forward approach to DNS is simply finding out the IP address of a domain. People tend to find it difficult to remember long strings of numbers. Instead, it's easier to remember a domain name that uses words.

However, electronic devices use streams of 1s and 0s to communicate. The only way for one computer to communicate with another is by unique identification. The method of identification used on the Internet is IP addresses.

Here are the simple steps for DNS resolution:

  1. A user enters a domain name into their Internet browser, like www.whatismyip.com.
  2. The computer sends the domain name as a DNS request to the user's Internet Service Provider (ISP).
  3. The ISP determines if it has the IP address associated with that name.
  4. If it does not, the ISP forwards the request to other providers in an effort to locate the DNS record that contains the data.
  5. Once the record is found, the IP address of the domain is returned to the user.
  6. Now, the user's computer can communicate directly with the server.

Many people compare DNS to a phonebook, which is an oversimplification of a very complex system. The world wide web provides the fundamental function of inter-connectivity, which is much more than the telephone relays of before.

Reverse DNS Lookup

In a reverse DNS lookup, the steps are the same except that it starts out with an IP address and returns with the domain name. In reality, this can take a while. And when a DNS is unable to find what it needs, whether it is a domain name or an IP address, we end up with the screen we all hate that states that "this webpage cannot be found." This is due to the servers being busy or the web browser timing out.