What is the DNS? Short Guide to the Domain Name System and Possible Errors

What is the DNS? Short Guide to the Domain Name System and Possible Errors

Have you ever asked yourself what exactly your browser does when you click on a link? There's actually nothing complicated behind it – but knowing a bit about the Domain Name System (DNS) will make troubleshooting you find yourself having to do a lot simpler. We explain what's behind the DNS and also explore typical sources of errors and their solutions. Have fun reading! 

What exactly is the DNS? 

A website is created by data that your browser downloads from a server with a specific address. Data exchange on a network requires an individual, unique identifier for each computer so that the data is obtained from the correct source. This identifier is called an IP address. 

IP addresses are written according to IPv4 in the format xxx.xxx.xxx.xxx, where each x represents a digit, or even more complicated according to IPv6 in a hexadecimal notation. It's impossible to remember many of these addresses without writing them down. Most people would make a list that maps an IP address to a name. And that's exactly what the Domain Name System does – and why it's often referred to as the "telephone book of the internet". 

This system translates human language into computer language, so to speak, because when you say, "I want to go to Google", the machine has to understand "connect to the IP address of the Google server and load the content". The domain in this case is google.com and represents human language. It always has a naming part (called the second level domain) and an ending (called the top level domain). This naming makes sense because an address is read from the back to the front in a DNS lookup and the .com thus becomes relevant first in google.com. 

DNS Lookup: How browsers load a website 

The interaction of four servers ensures that the delivery of the IP address of a domain is delivered to the client (i.e. the web browser). 

DNS query
Source: Graphic by Zhou Li (own adaptation: SLD nameserver replaced by authoritative nameserver)

In principle, the process can be compared to the procedure in a pharmacy. You (the web browser) come in and ask the person behind the counter (DNS recursor) for a medicine (the domain name). Either they know immediately which product it is and where it is (name and IP are in the cache). If not, they need to look for the medicine in their system. To do this, they first search for a category with associated shelves (root name server). This could be, for example, natural remedies, painkillers, antibiotics or similar. In the next step, the specific shelf is determined (TLD nameserver), and finally the drug they're looking for and its exact location on this shelf are identified (authoritative nameserver). 

DNS example pharmacy
Source: Graphic by Zhou Li (own adaptation for pharmacies example)

In a final step, the browser now sends an HTTP request to the IP address received from the DNS recursor. If successful, the browser loads the website data from the server and finally displays it.

Are there any errors in the DNS lookup?

If errors occur during the DNS lookup, the domain provider is usually responsible. In this case, the only thing that helps is patience until the domain provider has fixed the problem.

A link in your address bar is therefore resolved from right to left. Only the rightmost part, which is separated by a "/", does not belong to the relevant part of the link. Sometimes it's not even there but if it is, it only shows the resource of the server that the browser wants to access via HTTP request. This part has no meaning for the DNS. 

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A record and AAAA record

The A record is the entry that assigns an IPv4 address to a domain. At the same time, there's also the AAAA record for an IPv6 address. There are other so-called resource records, but they're not relevant for our topic today. You can find an overview of the most important DNS entries in our Help Center

To clear up one common misunderstanding here – your domain provider is not necessarily your web host. You set the DNS records at the domain provider! You can set your A record and the AAAA record as follows:

  1. Visit your domain provider's website and log in.
  2. Go to the resource records in your domain settings. 
  3. Find the A record and the AAAA record and change them so that the IP address of your server is assigned to the correct domain.
  4. Also enter all possible subdomains here. The domain raidboxes.io is not automatically resolved to the same IP address for www.raidboxes.io! This is a very typical source of error. It's better to make sure a second time that all possible entries are also stored here!

At Raidboxes you can check the DNS settings in your Dashboard and linka domain to your Box .

What is the DNS? Short Guide to the Domain Name System and Possible Errors

A green tick shows you the IP address in the A record of your domain provider is correct. If the entries are incorrect, an orange exclamation mark is displayed instead.

raidboxes dashboard DNS warning

A practical tool for quickly checking the resource records of a domain is Google Dig. The tool is almost self-explanatory – simply enter the domain and you can see the corresponding records.  

Assistance for DNS troubleshooting

If your domain is resolved to the wrong IP, you'll usually see "page not found" or simply nothing will be displayed at all. If everything is correct with the entries, you should first check whether your domain provider is currently having problems with performance. If this is the case, you should contact them before you continue to search for the error. Otherwise, it's advisable to go in the direction of the Internet, starting with your browser and clearing all DNS caches, if possible.

When you visit a website, your browser and operating system store the IP address of the site for a few hours. The DNS cache is very easy to clear in these two cases. In the browser, you only have to empty your normal cache. This can be done in the most common browsers such as Google Chrome and Mozilla Firefox under Settings then Security/Data Protection.

clear DNS cache browser

Typical source of error

One typical source of error is when your browser wants to access a domain, but there's still an incorrect IP address in the DNS cache.

If clearing the browser cache wasn't enough, you should clear the DNS cache of your operating system. This can be done as follows:

  • Call up your computer's console (cmd, or "Terminal" on Macs).
  • Depending on your operating system, execute the following command on it:
  • Windows: ipconfig /flushdns
  • Linux/Mac: sudo lookupd -flushcache
  • Mac OS X from10.5: dscacheutil -flushcache

If it still doesn't work, you can try restarting your router. If this doesn't help either, the problem is the DNS cache of your Internet provider. Unfortunately, you can only wait and see what happens here. It can take up to 48 hours to synchronize the DNS servers and the DNS cache in the individual routers (including your router). The only thing you can do is try again at a later time. 

A last sensible attempt to solve a DNS issue is to access the domain via another connection, e.g. mobile data or VPN, and check whether this works. If the page is displayed via another connection, you just need a little patience as your router simply need to synchronize its DNS cache with the DNS servers. Sadly, there's no way to speed this up. If your site is not displayed even with a different connection, you can check the DNS settings again with the already mentioned A Record and AAAA Record of your site. . If the records are set correctly, however, the same applies as before – you can only wait for the DNS cache of your router and the DNS servers to be synchronized. 

A DNS-related inaccessibility of your website is a condition that in most cases will resolve itself with patience and a little waiting. It's not actually a "problem" but a necessary process – the internet works exactly as it should because of this process. If the problem on your website is still present after 48 hours, however, and none of the tips mentioned here help, please contact our support. In these cases, it's most likely not the DNS. But even if you are unsure whether you have done everything correctly or whether you've understood the correlations correctly, please feel free to contact our support anyway! 

Summary: the DNS

The DNS is not complicated – it simplifies a lot and makes it possible to use names or similar as IP addresses. Each domain has so-called resource records such as the A record, which enables the assignment of name to IP. If something stops working, it's relatively easy to find the fault as there are only a few possible interfering factors. Unfortunately, DNS-related problems require a little patience. Often you can only wait until the DNS caches have synchronized with the DNS servers. It's not possible to speed up this process as it's a fundamental part of the internet and it (unfortunately) only works this way.

Your questions and tips on the topic of DNS

What was your experience with the DNS so far? Do you have any questions or feedback? Feel free to use the comment function! Are you interested in current topics around WordPress, web design and online business? Then follow Raidboxes on Twitter, Facebook, LinkedIn or via our newsletter.

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