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How DNS works

by SW Team

DNS, or Domain Name System, is essential for navigating the Internet. They work like a telephone directory, translating domain names (such as "") into IP addresses, allowing easy access to websites and online resources. Their importance lies in simplifying navigation by eliminating the need to remember complicated IP addresses.

How DNS Resolution Works

DNS resolution is a fundamental process that allows Internet users to access websites efficiently. To understand it, it is important to understand the steps behind the process:

  • Request a Domain Name: When you type a web address into your browser, such as "", your computer does not know what IP address that name corresponds to. So it initiates DNS resolution by sending a request to a DNS server.

  • Look in the Local Cache: First, your computer checks its local DNS cache. This is where translations of domain names to IP addresses of websites you have recently visited are temporarily stored. If the translation is in the cache, the resolution process is skipped and the website is accessed immediately, speeding up browsing.

  • Query the Local DNS Server: If the translation is not found in the local cache, your computer communicates with a local DNS server. This server is provided by your Internet Service Provider (ISP) and is usually configured by default on your device.

  • Root DNS Server Lookup: If the local DNS server cannot provide the translation, it queries the root DNS servers. These servers are the ultimate authority in the Domain Name System and direct the request to the appropriate DNS servers for the particular domain extension (e.g. .com, .org, .es).

  • Query the Top Level Domain (TLD) Servers: TLD servers store information about domain extensions such as .com or .es. The root DNS server redirects the request to the appropriate TLD server.

  • Querying the Authoritative Server: The TLD server provides the IP address of the authoritative DNS server for the requested domain ( This server is the last step before reaching the server that stores the IP address of the specific website.

  • Obtaining the Final IP Address: Finally, the request reaches at the authoritative DNS server for the domain (, which provides the IP address associated with that domain name. This information is then sent back to your computer.

  • Access the Website: With the IP address obtained, your computer can now access the website you want. This process takes only a few milliseconds and allows you to surf the Internet without any problems.

Common DNS Problems

DNS problems are a common cause of Internet connectivity problems. To help you understand and deal with these problems, we have listed some of the most common DNS problems and their solutions. But if you want to know more about DNS configuration, here is a link to our manuals where we explain everything from how to manage your DNS zone to how to configure external DNS, click here to see the manuals. We also have another blog where we explain more information about DNS, click here to read the blog.

Problem 1: Slow DNS Resolution

Cause: This may be due to network problems, slow DNS servers or incorrect configuration.

Solution: Switch to faster DNS servers, such as some public DNS servers, or check the DNS settings on your device.

Problem 2: Inaccessible Websites

Cause: The inability to access a website may be the result of a DNS resolution failure or the site being blocked.

Solution: Try clearing the local DNS cache, switching to alternative DNS servers, or checking if the website is blocked by a firewall or content filter.

Problem 3: DNS Not Responding

Cause: This problem is usually related to router configuration, network problems or DNS server failures.

Solution: Reboot the router, check the Internet connection, or contact your Internet service provider if the DNS server is down.

Problem 4: Corrupted Cache

Cause: The local DNS cache can become corrupted, causing resolution problems.

Solution: Clear the DNS cache on the device to force a new resolution.

Problem 5: Incorrect Redirection

Cause: Can be caused by DNS server misconfigurations or malicious redirection attacks.

Solution: Check DNS settings, use secure DNS servers and keep security software updated.

Problem 6: DNS Spoofing

Cause: These malicious attacks can manipulate DNS resolution to redirect you to fake or dangerous websites.

Solution: Implement security measures such as DNSSEC (Domain Name System Security Extensions System) to protect against spoofing attacks.

Problem 7: DNS DDoS (Distributed Denial of Service Attacks)

Cause: DDoS attacks can overload DNS servers, resulting in reduced availability.

Solution: Internet Service Providers and DNS server administrators need to implement advanced security measures to mitigate DDoS attacks. For example, at SW Hosting we offer AntiDDoS free of charge.

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