What is the DNS? Settings and sources of error briefly explained

What is the DNS? Settings and sources of error briefly explained

Have you ever asked yourself: What exactly does my browser do when I click on a link? There's actually nothing complicated behind it - but knowing about the Domain Name System (DNS) will make troubleshooting a lot easier. We explain what is behind the DNS and how to check your DNS settings. We also look at typical sources of errors and how to solve them. 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". In this case, the domain is google.com and represents human language. It always has a name-giving part (the so-called second level domain) and an ending (the so-called top level domain). This naming makes sense, as an address is read from back to front in DNS lookups (or DNS queries) and the .com is therefore relevant first for google.com. 

DNS Lookup: How browsers load a website 

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

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 located (name and IP are in the cache). If not, it must search for the medicine in its system. To do this, it first searches for a category with associated shelves (master 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 medicine being searched for and its exact location on this shelf is 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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DNS settings: A Record and AAAA Record

The A record is the entry that assigns an IPv4 address to a domain. Similarly, there is the AAAA record for an IPv6 address. There are other so-called resource records and DNS settings, but these are not relevant to 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? Settings and sources of error briefly explained

You can see with a green tick whether the IP address in your domain provider's A record is correct. If the DNS entries are incorrect, you will see an orange exclamation mark.

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 resolves to the wrong IP, you can usually tell by the fact that "site not found" or simply nothing at all is displayed. I have already introduced you to the records - if everything is correct with the DNS 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 looking for the error. Otherwise, we recommend starting with your browser and working your way to the Internet and clearing all DNS caches if possible.

When you visit a website, your browser and operating system save the IP address of site for a few hours. The DNS cache is very easy to clear in these two cases: In the browser, all you have to do is clear your normal cache. You can do this in common browsers such as Google Chrome and Mozilla Firefox under Settings - Security/Privacy.

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 the console of your computer (cmd, or "Terminal" on Mac).
  • 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. 

One last sensible attempt is to access the domain in another way, for example via mobile data or a VPN, instead of using a Wi-Fi connection and check whether this works. If the site is displayed via a different connection, a little patience is guaranteed to help you - because your router still has to synchronize its DNS cache with the DNS servers. Unfortunately, there is no way to speed this up. If the site is not displayed even with a different connection, you can check the DNS setting again with the aforementioned A record and AAAA record of your site . However, if the records are set correctly, the same applies as before - unfortunately you can only wait for the DNS cache of your router to be synchronized with the DNS servers. 

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 - but 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 is relatively easy to find a fault, as there are only a few possible disruptive 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 is not possible to speed up this process as it is a fundamental part of the internet - and it (unfortunately) only works in 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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