A DNS server converts a domain into an IP address. It acts as a kind of telephone book in a network and translates domain names that are incomprehensible to the computer into IP addresses. DNS saves users from having to remember IP addresses, the domain name is sufficient to reach a website.
Once you are connected to an IP network with your PC, smartphone or other device, a component on the network acts as a kind of directory assistance. This component translates host or domain names into IP addresses in the background and allows you to enter an address in the form "". In a local network, this task is usually performed by the router. If you are on the Internet, the DNS server of your provider will do this for you.
As mentioned at the beginning, the DNS server acts as a telephone directory assistance. Every url that you enter in your browser, every server for gambling, every connection to the streaming service … everything is first converted into an IP address via the DNS server and only then forwarded to the target server. At least this is always the case for the first request - after that, depending on the system, the request can also be cached (see DNS cache).
These requests usually run very fast, in daily life with your digital helpers you will hardly notice this. But if you want to optimize the last bit, it's worth a look at the DNS servers of Google. These are free to use and extremely fast. Read our instructions and find out how you can use Google's DNS servers and speed up your Internet.
Read and delete DNS cache under Windows
If you change the DNS server at your site, for example because you want to use the Google servers, some queries may be answered by your local system. These queries are then answered from the so-called resolution cache. Restarting the system will solve the problem, but you can avoid this by using a command at the command prompt. You can also look into the DNS cache and find out which domain names are in the cache.
DynDNS: Dynamic DNS for external access
If you want to access your computer at home from the Internet, you will soon notice that the IP address changes every time you dial up or force your router to disconnect. Services like DynDNS can help here. These ensure that your PC or router always transmits your current IP address to the DynDNS service. The IP address is then saved together with the corresponding domain name, so that you only have to remember the domain name to access your computer.
Basically you have two possibilities how to set up a DynDNS: Either you configure it on the router or directly on your PC. If you have a router, we recommend that you configure the DynDNS on the router, which gives you more flexibility. You can also use port rules to make several computers in your home network accessible from the outside.
At this point we will explain the general setup on the PC in combination with the "DynDNS Updater". How to set up DynDNS on the router is explained using the Speedport-Router and various DynDNS services. For professionals, the self-build instructions are worthwhile: DynDNS: Build your own free alternative with Fritz!Box.
DNS server to bypass Geo-IP locks
Country blocks may prevent you from accessing certain content. DNS services can help you here as well. Services like Unblock-Us can help you here. Using HBO Nordic and Unblock-Us as examples, we explain the advantages and disadvantages. Further alternatives and background information on the technology called "SmartDNS" can be found in the linked special.
Security: Prevent DNS Spoofing
In your own network you don't have to worry about your DNS server, even the DNS assigned by the providers is rarely the target of so-called DNS spoofing attacks. The situation is different in networks with several less trustworthy people. Here, an attacker could try to manipulate the DNS queries, for example to route them through your own server. The DNS queries are then answered via the attacker's computer, giving the attacker the opportunity to foist other pages on users. For example, the attacker can exchange the online banking page and intercept the account data.
If you are often in public networks, we will explain here how you can protect yourself from DNS spoofing in networks.