DNS Servers and IP Addresses
Computers and various devices that use the internet depend on IP addresses to send a user's request to the website they are attempting to reach. Without DNS, you would have to keep track of the IP addresses of all the websites you visit, similar to carrying around a phone book of websites all the time. The DNS server allows you to type in the name of the website. It then goes out and gets the right IP address for you. Armed with the IP address, your computer (or browser) can bring you to the site.
For instance, if you input www.fortinet.com in your web browser, that URL, on its own, cannot bring you to the website. Those letters cannot be “read” by the servers that connect you with the site. However, the servers are able to read IP addresses. The DNS server figures out which IP address corresponds with www.fortinet.com and sends it to your browser. Then the website appears on your device’s screen because the browser now knows where to take your device.
DNS Server Not Responding? What Does That Mean?
You may get a message that says “DNS server isn’t responding” after entering a domain name in the URL bar of your browser.This means there was an attempt to communicate with the DNS server, but the server failed to return a result. This could be due to a few different things:
- Your internet connection is weak or unstable, making it hard for your browser to communicate with the DNS server
- Your DNS settings or browser need to be updated
- There is an issue with the DNS server, such as a loss of power at the data center where it is housed
Best DNS Servers
Here are some of the top DNS servers available:
- Cloudflare 1.1.1.1.This is a simple-to-use DNS service that comes with tutorials for all of the most popular operating systems, such as Mac, Windows, Android, iOS, and Linux. Users can also use Cloudflare’s service to block adult content.
- Google Public DNS. The Google Public DNS service is different from Cloudflare’s in that it is designed for more technically adept users. But you can find tutorials if needed.
- Quad9. Quad9’s DNS service is renowned for its fast performance. It also claims to block malicious sites using threat intelligence data.
Browser DNS Caching
The operating system (OS) used by your device stores DNS resource records through the use of caching. Caching prevents redundancy when someone tries to go to a site. This, in turn, reduces the amount of time it takes to get to the website. If the device you are using recently went to the page it is trying to access, the IP address can be supplied by the cache. In this way, the website request can be completed without involving the DNS server.
The DNS cache, therefore, helps streamline the DNS lookup process that would otherwise be necessary to link a domain name to an IP address. This makes the process of getting to the website much faster.
OS DNS Caching
The operating systems of many devices are capable of maintaining a local copy of DNS lookups. This makes it possible for the OS to quickly get the information it needs to resolve the URL to the correct IP address.
How to Perform a DNS Lookup
Each domain has DNS records, and these are pulled by nameservers. You can check the status of the DNS records associated with your domain. You can also examine the nameservers to ascertain which records are being pulled by the servers. On a Windows computer, for example, this is done using the NSLOOKUP command. Here’s how to do it:
- Access the Windows command prompt by going to Start >> command prompt. You can also get to it via Run >> CMD.
- Type NSLOOKUP and then hit Enter. The default server gets set to your local DNS, and the address will be your local IP address.
- You then set the type of DNS record you want to look up by typing "set type=##" where "##" is the record type, then hit Enter. You can also use A, AAAA, A+AAAA, ANY, CNAME, MX, NS, PTR, SOA, or SRV as the record type.
- Enter the domain name you want to query. Hit Enter.
- At this point, the NSLOOKUP returns the record entries for the domain you entered.
What is a DNS Revolver?
A DNS resolver is also referred to as a recursive resolver. It is designed to take DNS queries sent by web browsers and applications. The resolver receives the website URL, and it then retrieves the IP address that goes with that URL.
What are the Types of DNS Queries?
During the DNS lookup process, three different kinds of queries are performed. The queries are combined to optimize the resolution of the DNS, saving time.
- Recursive query
- Iterative query
- Non-recursive query
