The DNS is the reason websites have such catchy domain names, but most people don’t know what is DNS and…
The Domain Name System or DNS server is a server specifically designed for matching website hostnames (like yourdomainname.com) to their corresponding IP or Internet Protocol addresses. Consider a DNS server as a colossal internet phonebook. This contains all the addresses necessary to render domain names as their web pages to the end-user. Every device connected to the internet contains a unique IP address which helps identify it called IPv4 or IPv6 protocols. Similarly, web servers hosting websites behave the same way. For example, the IP address of one of Hosting.uk’s servers located in mainland Europe is 18.104.22.168.
DNS servers act as a repository of millions of numbers and help us avoid memorizing the long numbers.
An important point to remember: IP addresses contain a combination of numbers. In the IPv6 system there are more complex alphanumeric codes.
In other words, a DNS server does the heavy lifting of connecting us through the internet. DNS servers automatically translate the names of a website, into numbers so the server can load the correct web page.
To better understand the role of a DNS Server, it is first imperative to know about the Domain Name System. A Domain Name System stripped down to its basic form is a phonebook. It’s sole purpose is to help us connect to webpages. In the same way, we lookup an individual’s phone number in a phonebook, the DNS matches a website or domain name to the corresponding IP address.
Simply put, a server is a device or a program dedicated to rendering services to other programs. This is often referred to as clients. DNS clients, which are nowadays built into most modern mobile operating systems and desktops enable web browsers to interact seamlessly with DNS servers.
To reiterate, a DNS is a system that holds records of domain names and their corresponding IP addresses. This enables web browsers to find the correct IP address that corresponds to a URL, hostname/domain. When we try to access a website, we typically type Google or yahoo, into the address bar. At this point, your web browser needs to find the exact IP address so that it can load the content from the website. A DNS server acts as a translator as it converts domain names to IP addresses enabling the resources to be loaded from the website’s server.
In some instances, websites can have more than one IP address corresponding to one domain name. For example, mega-sites like Google will have users querying a server from various parts of the world at once. The server that a computer from Hong Kong tries to query will possibly be different from the one a different computer from say Mexico. Even in a scenario where you enter it in the browser at the exact time.
DNS caching involves the storage of DNS data on the DNS records near a requesting client. The process enables faster DNS query resolve. This eliminates the problem of additional queries further down the line and it improves page load times and bandwidth consumed.
DNS records stored in the DNS cache for an amount of time is the ‘time to live’ or TTL. A TTL (period of time) is imperative as it determines how fresh the DNS records are and whether or not it matches recent updates made to IP addresses.
DNS caching can be created either at the browser level or at the operating system – OS level.
Subsequently, web browsers typically store DNS records for a set period of time, it is normally the first place checked when an end-user makes a DNS record. From the browser, there are fewer steps for checking the DNS cache and creating the DNS request to an IP address.
Once a DNS query departs an end user’s device, the next destination where a match is sought after is at the operating system level. Stub resolver is a process carried out inside the operating system, which checks its DNS cache to ensure it has the record. If it doesn’t have the record, the query is then sent outside of the local network to the Internet Service Provider (ISP).
Remember, a DNS is responsible for translating the website or web page name, to the IP address. When you type the domain name, we call this a DNS query and the DNS resolution is the process of finding the corresponding IP address.
A DNS query can fall under three types: a recursive query, non-recursive query, or iterative query.
When you enter in a DNS query it goes through a few different layers or servers before there is a resolution.
A DNS lookup is the process by which a DNS server returns a DNS record. A DNS lookup involves the query of the hostname from the web browser to the DNS lookup process on the DNS server and back again. The server carries out the first step of the DNS lookup process. This starts the sequence of steps that ends in the URL being decoded into the IP address for loading the web pages is known as a DNS resolver.
First, the user-entered domain name (hostname) query travels from the web browser through the internet. Then the DNS recursive resolver intercepts. The recursive DNS server then sends a query to the DNS root server which replies with the address of the TLD server responsible for storing the domains.
The resolver then creates a DNS request for the corresponding domain’s TLD. After it receives the IP address of the domain nameserver. As a final step, the recursive DNS server queries the domain nameserver and is then returned with the IP address to send to the web browser. Subsequently, at the end of this DNS lookup process, the browser can then submit a query for individual web pages through HTTP requests.
These steps make up a standard DNS lookup process. However, these steps can also be shortened via the use of DNS caching. DNS caching allows for the storage of the DNS lookup information locally on the browser. The OS (operating system), or a remote DNS infrastructure, allows it to skip some of the steps in the process for quicker loading of a web page.
DNS is the defining system for DNS protocol. A DNS protocol is a communication exchange and data structure that is specified in detail and used in the DNS. This comes under the umbrella of the Internet Protocol Suite (TCP/IP). Furthermore, the DNS keeps a blackhole list of IP addresses known for sending spam emails. Mail servers, therefore, can be configured based on this blackhole list to flag or reject messages that are suspected of being spam.
DNS servers can file for a multitude of reasons, such as power outages at the server site, cyberattacks led by cybercriminals, and hardware malfunctions. During the earlier days of the internet, DNS server outages had a moderately high impact. However, thankfully, today we have advanced beyond that and there is a lot of redundancy built into DNS servers.
For example, there are multiple instances of the root DNS servers, TLD nameservers, and most ISPs (internet service providers) have implemented backup recursive resolvers for their users.
Additionally, individual users can opt to use public DNS resolvers. In fact, most popular websites also have numerous instances of their authoritative nameservers with built-in redundancy.
In the event of a major DNS server outage, some users may experience delays in web page load. This is because of the number of requests being received by backup servers. However, it would probably take a DNS outage of a colossal proportion to make a significant area of the internet unavailable. Something like this happened in 2016 when DNS provider Dyn was the victim of one of the largest-scale DDoS attacks in internet history.
When it comes to the vulnerability of DNS servers, they are most often targeted by cybercriminals using two methods. These popular DDOS attacks target DNS servers. They aim to knock a portion of the internet out, they are DNS amplification attacks and DNS flood attacks.
We hope this article was informative and gave you a full rundown of what DNS servers are. Now you know how they work and how integral they are to the overall function of the internet. At Hosting.uk we offer DNS management and reliable hosting to cater to a wide scope of needs. Register your domain today and launch your website of the most secure UK hosting network.