DNS for dummies: How domains and networks interact?

DNS, or Domain Name System, translates domain names (like google.com) into IP addresses (a series of numbers) that computers use to identify each other on a network. This process happens behind the scenes whenever you browse the web, send an email, or use an app. Without DNS, we’d have to remember IP addresses of all our favorite websites, instead of simple names.

This guide will explain DNS in simple terms, breaking down how it works and why it's so crucial for the internet as a whole.

Basics of DNS

Think of DNS as the internet's phonebook. Just like you use someone's name to look up their number in the phonebook, DNS lets you type in a website’s name (like amazon.com) to find its IP address (the website’s “phone number”). This IP address is a series of numbers (for example, 142.250.184.14) that tells your computer where to find that website on the internet.

To break it down further:

• Domain name: A human-readable name for a website or network resource.
• IP Address: A set of numbers that can uniquely identify each device attached to a computer network.
• DNS server: A computer that stores and maintains DNS records.

So, when you type a URL in your web browser, your computer queries a DNS server. The DNS server checks its records and returns the IP address associated with that domain name. Your computer then uses the IP address to connect to the website's server.

Key components of a DNS

The DNS system has a few key parts that work together to direct you to the right website:

• DNS resolver: This is the software on your computer or network device that initiates the DNS lookup process. It sends a query to a DNS server.
• DNS server: A computer that stores and maintains DNS records. Here are two types of DNS servers:
  • Authoritative Server: The primary server that holds the authoritative DNS records for a specific domain.
  • Recursive Resolver: A server that can handle DNS queries by contacting other DNS servers as needed.
• DNS Record: A database entry that associates a domain name with its corresponding IP address or other information.
• DNS Hierarchy: A hierarchical structure of DNS servers that helps distribute the load and improve performance. The top-level domain (TLD) servers, such as .com, .net, and .org, are at the highest level.

Different types of DNS records

DNS records are like instructions that tell the DNS system how to handle different domain names. There are several types of DNS records, and each one serves a specific purpose:

• A Record (Address Record): Maps a domain name to an IP address.
• CNAME Record (Canonical Name Record): Redirects traffic from a domain to another domain.
• MX Record (Mail Exchange Record): Depicts the mail server to which the emails will be sent for this domain.
• TXT Record (Text Record): Holds text information that can be used for verification and security purposes.
• NS Record (Name Server Record): Indicates which server is authoritative for a domain.

The DNS resolution process

Here’s a step-by-step breakdown of the DNS resolution process:

1. When you type a domain name into your browser (for example, www.example.com), your computer first checks its local cache. The cache stores recent DNS lookups to speed things up, so if you've visited the site recently, your computer already knows the IP address.
2. If the IP address isn’t in the local cache, your computer sends a query to a DNS resolver (also called a recursive resolver). Generally, your internet service provider (ISP) will provide this resolver.
3. If the DNS resolver doesn’t have the IP address in its cache, it sends the query to a root nameserver. The root nameserver doesn’t know the exact IP address either, but it knows which TLD (top-level domain) server to ask next.
4. The root nameserver directs the DNS resolver to the TLD nameserver. For example, if you’re looking for www.example.com, the TLD nameserver for ".com" will handle the request. This server helps narrow down the search to the correct domain nameserver.
5. The TLD nameserver then directs the query to the authoritative nameserver, which holds the specific DNS records for the domain you’re trying to reach. This server knows the exact IP address for the domain (like www.example.com).
6. Once the authoritative nameserver finds the IP address, it sends the information back to the DNS resolver. The resolver then stores this IP address in its own cache, so it doesn’t have to repeat the process if someone else needs to visit the same site. It also sends the IP address back to your computer.
7. With the IP address in hand, your browser connects to the web server associated with the IP, loads the website, and displays it to you.

This whole process happens in a matter of milliseconds, so it feels almost instant to the user.

Managing domains

Next, we will discuss how you can go about purchasing, registering, and monitoring domains.

How to purchase a domain name

Here’s how to buy a domain name:

1. Start by choosing a registrar, such as Namecheap, GoDaddy, and Google Domains. Registrars are companies that sell domain names.
2. Use the registrar’s search tool to find an available domain that fits your needs. If your preferred domain is already taken, you can explore alternatives like different extensions (.net, .org) or variations of the name.
3. Domain prices vary based on the name’s popularity, extension, and the registrar itself. Be sure to check if there are any extra costs for privacy protection or renewals.
4. After choosing your domain, follow the steps to complete the payment and purchase.
5. During registration, you'll need to provide contact details (name, email, address). This information will be added to the WHOIS database, which lists all domain owners.
6. Once done, the domain is yours for the duration of the registration period (usually 1 year).
7. To avoid losing ownership, enable auto-renew or set reminders to manually renew the registration before it expires.

Monitor for privacy and security

There are different steps you can take to ensure that your domain and associated private information remains safe:

• Enable WHOIS privacy. Most registrars offer this feature, which hides your personal contact information from public records. It’s a simple way to protect yourself from potential spam and scams.
• Enable two-factor authentication (2FA). This will ensure that even if someone gets hold of your password, they won’t be able to access your domain without a second form of authentication (like an OTP).
• Ensure that the email associated with your domain is secure and up to date, as it's used for important domain communications.

How to configure DNS records

Once your domain is registered, you may want to configure some DNS records. Here’s how to do that:

• Once logged into your domain registrar account, navigate to the DNS settings section. Here, you’ll find a list of records that direct traffic.
• To connect your domain to a web server, you’ll need to create an A record. This will map your domain to the IP address of the web server hosting your site.
• If you want to use a subdomain (like blog.example.com) that points to another site, set up a CNAME record. This allows one domain to point to another without using an IP address.
• To direct email traffic, you'll need to set up MX records. These point to the mail servers responsible for handling emails sent to your domain.
• Set up TXT records to add security features like Sender Policy Framework (SPF) or DomainKeys Identified Mail (DKIM).
• Once you’ve added or edited your DNS records, save the changes.
• The last step is to wait. DNS updates can take anywhere from a few minutes to 48 hours to fully propagate across the internet.

Common DNS issues and troubleshooting

Like any complex system, a DNS can encounter issues. This section discusses and dissects some common ones:

DNS resolution failure

Description: This happens when the DNS system can't translate a domain name into an IP address.

Symptoms:

• "Server not found" or "DNS address could not be found" errors in your browser.
• Unable to access any websites.

Troubleshooting:

• Restart your router and device to refresh the network connection.
• Clear your local DNS cache.
• Check if the DNS server you are using is working properly by switching to a public DNS service like Google DNS (8.8.8.8) or Cloudflare (1.1.1.1).
• Verify the domain’s DNS records using online tools like DNSChecker or MXToolbox.

DNS propagation delay

Description: DNS changes (like new records) take time to update across the internet.

Symptoms:

• Website or email not available after making DNS changes.
• Only some users can access the site.

Troubleshooting:

• Be patient — DNS changes can take up to 48 hours to fully propagate.
• Use online tools like "What's My DNS" to check if the changes have been applied in different locations.
• Clear your browser cache and flush your local DNS cache.
• Use a VPN to test from different geographic locations to see if the changes are available elsewhere.

Domain name conflict

Description: Two domains are mapped to the same IP, causing confusion or access issues.

Symptoms:

• Your domain redirects to another website.
• Mixed content from multiple domains.

Troubleshooting:

• Check your DNS settings to ensure that no other domain shares your IP address (unless intended).
• Review CNAME and A records to confirm that they are pointing to the correct locations.
• Contact your web hosting provider and ask them to verify that there are no misconfigurations on the server side.
• If using a content delivery network (CDN), ensure that it is configured correctly to avoid conflicts.

DNS server not responding

Description: Your computer or router cannot connect to the DNS server.

Symptoms:

• You get a "DNS server isn't responding" error message.
• Websites fail to load on all devices in the network.

Troubleshooting:

• Restart your router and modem.
• Try switching to a different DNS server (e.g., Google DNS or Cloudflare).
• Disable your firewall or antivirus temporarily to check if it's blocking DNS requests.
• Check if your internet connection is working properly — you can do this by trying to connect to the internet with a different device or network.

Incorrect DNS records

Description: Misconfigured DNS records cause issues with website access or email delivery.

Symptoms:

• Website is down, or its subdomains are inaccessible.
• Emails are not being received.

Troubleshooting:

• Double-check your DNS records (A, CNAME, MX, etc.) for accuracy.
• Ensure that the IP addresses or hostnames in your records are correct.
• Test your DNS records using tools like MXToolbox to verify proper configuration.
• If you’ve recently moved your website or email to a new host, make sure that the DNS records were updated accordingly.

Expired domain registration

Description: Your domain registration has expired and your website or services have become unreachable.

Symptoms:

• Website is down with no clear error.
• Unable to receive emails linked to the domain.

Troubleshooting:

• Log into your domain registrar to check your domain’s status and renew it if expired.
• Enable auto-renew to prevent this from happening in the future.
• Ensure that your contact information is up to date with the registrar, so that you get renewal reminders.

Misconfigured TTL (Time to Live)

Description: The TTL value determines how long DNS records are cached. Misconfigured TTL can lead to outdated records being used.

Symptoms:

• Changes to DNS records take much longer than expected to propagate.
• Different users see different versions of your website.

Troubleshooting:

• Set the TTL value to a lower time (e.g., 300 seconds) when making changes to DNS records, so they propagate faster.
• After changes have been confirmed, adjust the TTL back to a higher value (e.g., 86,400 seconds) to improve caching and reduce DNS lookup times.
• Flush your local DNS cache after changes to ensure that you're viewing the latest version of the records.

Reverse DNS lookup failure

Description: Reverse DNS translates an IP address back to a domain name. Failure can cause issues with email services or IP verification.

Symptoms:

• Emails being flagged as spam or not delivered.
• Some services are unable to verify the legitimacy of your IP address.

Troubleshooting:

• Ensure that the reverse DNS (PTR) record is set up correctly with your hosting provider.
• Use tools like MXToolbox to check for reverse DNS issues and troubleshoot email delivery problems.

IPv6 DNS issues

Description: Issues arise when DNS records for IPv6 addresses (AAAA records) are misconfigured or missing.

Symptoms:

• Users on IPv6 networks can’t access your website, while those on IPv4 can.
• Intermittent connectivity issues depending on the user’s network setup.

Troubleshooting:

• Ensure that you have an AAAA record configured if your server supports IPv6.
• Verify that the IPv6 address is correct and reachable.
• Use online tools like “Test Your IPv6” to confirm that both IPv4 and IPv6 are functioning properly for your domain.

DNS security

Finally, this section sheds light on the security aspects of DNS and what steps you can take to stay protected from common attacks.

What cyber attacks are DNS servers vulnerable to?

DNS servers are a prime target for attackers because they play a key role in directing traffic on the internet. Here are some common DNS attacks:

• DNS spoofing (Cache Poisoning): Attackers inject false information into a DNS resolver’s cache, redirecting traffic to malicious websites without the user’s knowledge. This is often used in phishing schemes.
• DDoS (Distributed Denial of Service) attacks: Overwhelms DNS servers with excessive requests, causing them to crash or become unresponsive. This can render websites inaccessible.
• DNS amplification attacks: A type of DDoS attack where the attacker sends a small request to a DNS server that results in a large amount of traffic being directed towards the victim, with the intention of overwhelming their system.
• Domain hijacking: Attackers gain unauthorized access to your domain name registration and change DNS settings to point users to malicious servers.
• Tunneling: DNS tunneling is used to bypass network security restrictions. It allows attackers to communicate with command and control servers by hiding data inside DNS queries.

How do you increase your DNS security posture?

Here are some key steps to strengthen DNS security:

• Use DNSSEC (DNS Security Extensions): DNSSEC adds an additional layer of security by digitally signing DNS data to guarantee its authenticity and integrity. This helps prevent DNS spoofing and cache poisoning.
• Implement DDoS protection: Choose a DNS provider that offers DDoS mitigation services to protect your DNS servers from being overwhelmed by malicious traffic. Cloud-based DNS providers like Cloudflare and Akamai can help absorb and neutralize large-scale attacks.
• Regularly monitor DNS records: Keep a close eye on your DNS records to ensure that they haven’t been tampered with. This will help catch unauthorized changes before they can cause any harm.
• Apply rate limiting: Rate limiting restricts the number of requests a DNS server will handle over a certain period. This feature helps prevent DDoS amplification attacks by reducing the potential for abuse.
• Encrypt DNS queries: DNS-over-HTTPS (DoH) and DNS-over-TLS (DoT) encrypt DNS queries between your device and the DNS server to prevent attackers from intercepting or modifying your DNS traffic.

Conclusion

DNS is a fundamental technology that enables the internet to function as smoothly as it does. Hopefully, the insights shared in this guide have deepened your understanding of DNS and will help you better manage your domains, troubleshoot issues, and safeguard your online presence against potential threats.

If you want to track the health and performance of your DNS servers in real time, don’t forget to try out the DNS Monitoring Tool by Site24x7.