Maab S.

03 Oct 2024

9min Read

What is DNS? A Beginner’s Guide to the Domain Name System

What is DNS? An end-to-end guide for beginners

DNS, or Domain Name System, is like the address book of the internet. It translates the website names you type into your browser, like www.google.com, into numerical IP addresses that computers use to identify each other online. We offer domain registration services.

This translation is crucial because:

Computers speak in numbers: Imagine the internet as a giant city. Each building (computer) has a unique address, but a long and complicated one – like a string of numbers (the IP address).
Humans speak in words: We wouldn’t want to memorize complex building numbers to visit our favorite stores (websites)! Thankfully, DNS acts like a phonebook for this city. You simply look up the website’s name (like “Google”) and DNS provides the corresponding address (IP address) to get you there.

How DNS works: the basics

We know that DNS converts domain names to IP addresses… but how? Here’s a simple breakdown of the steps involved:

When you type a domain name into your browser, it sends a query to your local DNS server. This server is like a neighborhood information center.
The local server first checks its own memory to see if it has recently looked up the domain name. If it has, it returns the IP address right away.
If the local server doesn’t have the IP, it sends a request to a root DNS server. The root server is like the main switchboard of the internet. It directs the local server to the appropriate top-level domain (TLD) server, such as .com, .net, or .org.
The TLD server then looks up the specific domain name within its zone file. A zone file is like a directory containing all the domain names and their corresponding IP addresses for that particular TLD.
If the TLD server finds the domain name, it provides the IP address to the local DNS server. However, the TLD server may not have the authoritative answer, especially for larger domains. In this case, it directs the local DNS server to the authoritative server for that domain.
The authoritative server is the ultimate source of truth for a domain’s IP address. It provides the IP address to the local DNS server, which then returns it to the browser.
Now that your browser has the IP address, it connects to the website and loads it for you.

This process happens quickly, so you don’t even notice it!

The role of DNS in the internet

We already know that DNS makes browsing easy by letting us use domain names for websites instead of IP addresses. Here are a few additional reasons why DNS is so important for the internet:

Scalability of the internet: DNS helps manage the billions of websites and devices on the internet. It allows new websites and services to be added without causing conflicts or slowing down the system.
Intelligent traffic routing: DNS helps direct internet traffic to the correct server. If a website has multiple servers, which most large websites do, DNS can route users to the best one based on factors like location and response time.
Supports email, apps, and more – DNS isn’t just for websites. It’s also used to route emails and support the functionality of apps, cloud services, and other online tools.
Helps with security – DNS is part of many security measures, like filtering malicious websites and blocking phishing attacks. Systems like DNS filtering can prevent users from accidentally visiting dangerous sites.

Key components of DNS

There are several components that work together to make a DNS function. We’ve touched upon them earlier, but now let’s examine each one in more detail:

Domain names and IP addresses

A domain name is the human-friendly name for a website, like www.hostafrica.com. An IP address is a numerical label assigned to each device connected to a computer network, including websites. It serves as the unique identifier for websites on the internet. An example of an IP address is 192.168.1.1.

DNS is responsible for mapping domain names to IP addresses. The mapping process starts when a domain name is first registered. During registration, DNS links the IP address to the domain, and stores this information in a zone file on a nameserver. This zone file is consulted during the domain lookup process, i.e. when we enter the domain name in the browser.

DNS servers and types

DNS servers are specialized computers that handle DNS queries and store information about domain names and their corresponding IP addresses. Here are the different types of DNS servers:

DNS resolver (or recursive DNS): This is the first server your device contacts when it needs to look up a domain. It either finds the IP address in its own memory or starts a search to find it.
Root DNS server: This server helps point the resolver in the right direction by identifying the top-level domain (TLD), like “.com” or “.org”.
TLD server: The TLD server directs the request to the correct DNS server for the specific domain, like google.com.
Authoritative DNS server: This server has the final answer. It holds the IP address of the domain and provides it to the resolver so your browser can connect to the website.

DNS queries and responses

A DNS query is a request made by your device to find the IP address of a domain name. There are three main types of DNS queries:

Recursive query: In this query, the DNS resolver is asked to find the exact IP address for the domain, no matter how many steps it takes.
Iterative query: In this case, the resolver may only provide partial information, like directing the query to another server for more details.
Non-recursive query: If the resolver already knows the IP address (because it’s cached in memory), it responds immediately without contacting other servers.

Why is DNS important for websites (and website owners)?

For website owners, understanding what is DNS is crucial, because it directly impacts how visitors access their sites. A proper DNS setup not only ensures that your site is always accessible, but it also plays a role in improving speed, security, and user experience.

How DNS impacts website performance

The time it takes for DNS to translate a domain name to an IP address can affect how fast a website loads. Faster resolution means quicker access for users.
If the DNS server is far from the user, it can slow down the request process. This is why it’s important to use a DNS provider with global servers, as they make sure to route users to the nearest servers for faster responses.
When DNS records are cached properly, repeat visitors will experience faster load times because their devices don’t need to look up the IP address again.
Low TTL values mean more frequent DNS lookups, which can slow things down. Higher TTL values reduce the number of lookups and improve speed, but setting TTL too high (e.g., several days or weeks) can make it difficult to update DNS records quickly in response to changes or outages.
DNS can help distribute traffic across multiple servers, ensuring that no single server is overloaded. This leads to faster response times, especially during high traffic.

Implications of DNS errors/misconfigurations

On the other hand, DNS errors or misconfigurations can negatively impact your website’s performance and accessibility.

If DNS is misconfigured, users may not be able to reach the website at all, leading to loss of traffic and potential business.
Incorrect DNS settings can slow down the loading of your website, compromising user experience and SEO.
Poor DNS configuration can open up security vulnerabilities, allowing hackers to redirect traffic to malicious sites.
DNS records are also used for email delivery. If not properly configured, emails may not reach their intended recipients.

Common DNS terms you should know

Next, here’s a glossary of DNS terms that you should know:

Term	Definition
DNS lookup	The process of finding the IP address associated with a domain name.
DNS record	Information stored in the DNS system that tells how to route traffic for a domain.
DNS management	The process of configuring and maintaining DNS records for a domain.
DNS zone	A portion of the DNS namespace that is managed by a specific organization or administrator.
TTL (time to live)	The time period for which a DNS record is cached before it’s refreshed.
Nameserver	A server that stores DNS records and responds to queries about a domain’s IP address.
DNS propagation	The time it takes for DNS changes to be updated across all servers worldwide.
DNS cache	Temporary storage of DNS lookup information on local devices or servers to speed up future lookups.
Forward DNS	The process of finding the IP address based on a domain name.
Reverse DNS	The process of finding the domain name associated with an IP address.
Primary DNS	The main server that stores the original DNS records for a domain.
Secondary DNS	A backup server that holds a copy of the DNS records from the primary server.
DNS load balancing	The process of using DNS records to distribute traffic across multiple servers.

Security and DNS – What you need to know

DNS, like any critical technology, has security vulnerabilities. Some common security concerns are:

DNS spoofing: Criminals manipulate DNS records to redirect users to malicious websites.
DDoS attacks: Distributed Denial of Service (DDoS) attacks overwhelm DNS servers, making them unavailable and disrupting website access.
DNS tunneling: Malicious actors use DNS to tunnel malicious traffic, evading security controls and exfiltrating sensitive data.
DNS cache poisoning: Attackers inject false information into DNS caches, leading to incorrect IP address resolution.

DNS security best practices

Here are some best practices to protect your DNS and establish secure connections every time:

Opt for a provider that offers security features by default, and has a strong reputation for uptime and protection against attacks.
Enable DNSSEC (DNS Security Extensions). It is a cryptographic protocol that helps prevent DNS spoofing and other attacks by verifying that the DNS responses are authentic and have not been tampered with.
Regularly check your DNS logs for unusual activity or unauthorized changes.
Keep your DNS r e cords and infrastructure up to date to ensure that you’re using the latest security protocols.
Restrict the number of recursive queries your DNS servers can handle to prevent abuse.

DNS in everyday life – Practical examples

Now that we have covered what is DNS, its components, significance, and best practices, let’s look into two real-life scenarios that illustrate the importance of DNS in everyday life.

Sending emails

When you send an email, DNS helps route it to the correct destination. Imagine you want to send an email to your friend at example@gmail.com. DNS is used to translate this domain name (example@gmail.com) into the IP address of the appropriate Gmail server. Without DNS, you’d have to know the exact mail server address yourself, which would be cumbersome and impractical.

Using apps

When you use apps on your phone, such as a weather app or social media, DNS helps these apps connect to their servers. For example, when you open the Facebook app on your phone, DNS translates the domain name (facebook.com) into the IP address of Facebook’s server. This allows the app to retrieve your news feed, updates, and other content.

Conclusion

DNS is a fundamental technology that keeps the internet running smoothly. Without it, our online experiences would be cumbersome, chaotic, and frustrating. We hope this blog has shed light on how DNS works and why it’s so crucial.