Category: DNS

What does Reverse DNS mean?

Reverse DNS is an absolutely beneficial instrument for every business. It will convert the IP address into the domain name. But what makes you think you’d want that? Let’s take a closer look at Reverse DNS to comprehend it better.

PTR record – definition

The PTR is a DNS record type that we use for Reverse DNS to connect IP addresses (both IPv4 and IPv6) to the domain name. For example, when receiving mail servers want to know where an email came from, they execute a rDNS lookup and seek for PTR records. The PTR records will ensure that the IP address is actually associated with the domain name.

The purpose of Reverse DNS

Reverse DNS, also known as rDNS, is a querying technique used by DNS (Domain Name System) to do a particular sort of query with an IP address (IPv4 or IPv6) as an input and a name record as an output (A record or AAAA record). It’s termed reverse because it works in the same way as a forward DNS lookup, which connects an IP address to a domain name.

If you wish to check a specific host, you can use rDNS. Each host connected to a network has an IP address as an identification. You can readily see the IP address, but you can also execute a reverse DNS lookup to view the domain name and decide whether or not to trust it.

When do we use a Reverse DNS?

Reverse DNS is really helpful. We can use it for a range of things:

  • rDNS is extremely beneficial to businesses. It ensures that all of their emails are effectively sent to their clients and that they are not labeled spam.
  • We use it to ensure that the IP address and domain name are identical in most cases. If they don’t match, a man-in-the-middle attack (phishing) with malicious intent is possible. When a discrepancy arises, it is a piece of sure evidence that a cybercriminal has altered the data, and there is a security risk.
  • Reverse DNS is commonly beneficial for owners of large IP networks to improve and organize them.
  • When looking through domain registration and registrar files, rDNS could be useful in locating the domain of a device that is attempting to crack a firewall, spammers, or hackers.

Can you check it?

Yes, you can. What only you need is a computer and IP address. But the verification depends on your Operating System. So let’s see the different possibilities, which are as follows:

  • On Windows

On the Windows operating system, you can use the Nslookup command. First, find the Command Prompt and open it. Then inside, type the following command:

nslookup 52.14.98.213

Note that this is an example of Internet Protocol. So you have to change it with the one which you want to make the verification.

  • On Linux and macOS

Here the procedure is similar. So first, you have to find the Terminal and open it. Inside, type the following command:

dig –x 52.14.98.213

The same applies here to changing the IP address.

Conclusion

Finally, we came to a conclusion. So you can safely assume that you understand what the Reverse DNS is for. It is really beneficial, and it’s worth giving it a chance!

Interesting DNS Terms & Definitions

Here are some interesting DNS terms you may not know yet. They are helpful both for beginner DNS administrators and more advanced ones. 

Dynamic DNS

Dynamic DNS automatically updates your IP address every time it is replaced. The Internet Service Providers (ISPs) are commonly changing it since it is easier for them to manage their large networks. For that reason, it is really useful to implement Dynamic DNS, for example, for your CCTV cameras for surveillance.

Anycast DNS

If you want to boost the DNS resolution process of your domain, you should consider Anycast DNS. It is a routing mechanism that works by placing one IP address into several name servers that are positioned in different points of the world. That way, the DNS request (DNS query) takes the shortest path, and the closest server provides the needed data.

DNSSEC

DNSSEC (Domain Name System Security Extensions) brings extra protection to your DNS (Domain Name System). It applies cryptographic authentication for the DNS data (DNS records) that goes around the Internet. Besides, it provides insurance for the origin of the DNS data and its integrity. 

DNS query

DNS query is the process of searching DNS data (DNS records). Usually, that is the IP address (A record or AAAA record), but it could be a different DNS record of a domain name. DNS queries are initiated by users every time they want to visit a specific website. The DNS resolver (Recursive DNS server) receives the DNS query and asks for the needed information from the Authoritative DNS servers.

DNS server

The DNS servers are two types:

Authoritative name server: It replies to DNS queries. It is a source of reliable data, and it doesn’t just contain cached replies from another name server. Moreover, it is able to answer requests that are related to domain names registered in its configuration system.

Recursive name servers: Its main goal is to receive the user’s DNS query and look for the desired information. They ask many servers until they find the answer. Typically, they are described as the link between the user and authoritative name servers.

DNS cache

The DNS cache is a method for saving the DNS records for a particular amount of time of the already requested domain name. It is a widespread method included in different devices, like computers, tablets, mobiles, and DNS resolvers (Recursive DNS servers). Its primary purpose is to minimize the amount of time for resolving a domain name. Moreover, it simplifies the assignment of the Recursive DNS server by reducing the number of complete DNS lookups for a precise domain name.

DNS propagation

DNS propagation is the amount of time required for spreading the new DNS information (DNS records) you made through the rest of the network. Let’s say you adjusted your A or AAAA record and replaced the IP address of a hostname, which should be distributed to all of the recursive servers. The process of DNS propagation could take from one hour up to 72 hours. 

Conclusion

So, now you know some very interesting and helpful DNS terms. For sure, they are going to help you improve the management of your DNS.