Tag Archives: DNS query

Get familiar with the DNS resolution process

The DNS resolution process is the core of understanding how the Domain Name System works. That’s why, in this article today, we will explore it. So, let’s start. 

DNS resolution description

Domain Name System (DNS) resolution is the procedure of acquiring an IP address (IPv4 or IPv6 addresses) through its domain. This is done to make life easier for online users. The easiest way to understand DNS resolution is to picture a phone book with the names of people in it. But because it’s so hard to remember their phone numbers, we don’t. The same idea applies to DNS resolution. It gets to its IP address via the domain name.

So let’s start from the beginning and observe how domain name resolution works.

DNS resolution process: Steps

The DNS resolution is accomplished in several phases. It begins when a user wants to connect to a website or domain name.

  1. Inside the browser, you type a domain name. That is how the DNS query is performed. A DNS lookup is followed to find an analogous IP address.
  2. When the DNS recursive server receives the query, it checks to see if the IP address is still in its cache memory. If you request that domain for the first time, the answer will be unavailable. As a result, the DNS recursive server will look for the address in the remaining servers – Root, TLD, and finally, the authoritative DNS server.
  3. The Root server is at the top of the DNS hierarchy and serves as the first stop in the lookup process. It provides information and redirects to the responsible Top Level Domain (TLD) server, such as.com,.info, etc.
  4. The TLD server will provide information on which nameserver is in charge of that specific domain name.
  5. The DNS recursive server can then query the authoritative DNS server for the domain’s IP address.
  6. Following the response submission, the Recursive DNS server can return to your browser with the information required to access the website. Furthermore, if you want to explore the site later, it will save the IP address in its cache memory.
  7. Finally, the browser loads the URL you typed.

Challenges of the DNS resolution process

  • Network disruptions are frequently brought on by problems with DNS resolution. A single DNS server error, such as a missing or mistyped IP address in an authoritative server, can have cascade failures for all of the services that communicate with it as contemporary technology builds more intricate and interconnected networks.
  • Another issue for this process is a security concern. We can agree that this process is not secure, and it is possible to be a target of criminals (DDoS attacks, DNS spoofing, etc.). So, it’s essential to take measures before happening. For example, Anycast DNS, DNESSEC, Dynamic DNS, Private DNS server, etc.
  • The recent consolidation of third-party DNS providers is the last but not least significant challenge. There is a single point of failure due to the dependence of several high-traffic applications on the same provider, which might cause service disruptions on a worldwide scale. The great majority of enterprises rely heavily on DNS providers to facilitate internal and external communication, making them prime targets for DDoS and cache poisoning attacks. Organizations in these situations have few options for mitigating an outage, mainly if they depend on a single source.

Conclusion

While there is only a brief wait for the user, there are several steps in the DNS resolution process. The DNS query, therefore, passes across multiple servers (Recursive DNS server, Authoritative DNS server, etc.). The good news is that this procedure goes by so swiftly that we can reach our destination quickly. So it’s great to know what occurs when we enter a domain name into the search engine, even as basic internet users. Congratulations then. You’ve advanced your understanding of this topic by one step.

​Recursive DNS server – Everything you need to know

The Recursive DNS server is an important actor within the Domain Name System (DNS). Its work is vital to get answers to the huge number of DNS queries that are sent every minute.

What is a Recursive DNS server?

A Recursive DNS is a seeker of information. It’s the one in charge of seeking the necessary DNS information to respond to the DNS queries sent by users.

What does a Recursive DNS server do?

A Recursive DNS server is constantly busy. Every DNS query becomes a new mission to accomplish for it. There is a user who wants to load a domain, then he or she sends its query through the browser. This is the call for the Recursive to work seeking the associated IP address to that domain. It has a couple of choices to explore for getting that IP address. But the Recursive will keep seeking until it accomplishes its mission. Once it gets the information, it will give it to the user’s browser. Only then will the user be able to load the domain.

The two alternatives a Recursive DNS has to achieve its objective are these:

  1. It will take a look within its cache. Recursive servers can store DNS data but only for a limited time. Domains are different among them, and they have different needs. Based on that, administrators will determine the Time to Live (TTL) for the DNS records. They can set up low or high values that will define the expiration of DNS records.
    To get the answer to a user’s query, a Recursive DNS server will check its cache. If the TTL of the IP address has not expired yet, it will find it and send it to the user’s browser. It will finish its task quickly. But, if the TTL has already expired, the Recursive will have to follow a longer path.
  1. It will search for the authoritative nameserver. A Recursive can communicate with different servers to know which is the authoritative nameserver of the requested domain. Then, it can directly ask the authoritative for the IP address. This alternative takes a bit longer.

Is a Recursive DNS server essential?

Yes, it is! A Recursive DNS is located between authoritative nameservers and the users. Without it, there won’t be a DNS resolution process. Its contribution is essential to find the IP addresses linked to the domains requested by the users. Thanks to their work, millions of DNS queries worldwide get a proper answer.

Does a Recursive DNS server mean any risk?

Yes, unfortunately, cybercriminals know the relevance of its role in DNS resolution and its position between the authoritative and users. This makes it a target to be exploited for launching malicious attacks (DDoS).

Moreover, some Recursive servers are public, meaning their IP address is visible. This makes them attractive and easy victims for criminals.

Conclusion

Now, you know everything about a Recursive DNS server. It works hard for Internet users and your domain.