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What is a DNS server?. DNS is the acronym for Domain Name System either Domain Name Systemwhich is the method used by the Internet to translate easy-to-remember domain names like wpseguro.com instead of your IP 178.33.117.45 so that they are understandable by people and easier than if it is about remembering numerical sequence, as is the case with IPs.
Every computer or device connected to the Internet needs an IP address and it needs to be unique so that it can be accessed from anywhere on the network.
Remembering IP numbers to access websites is a complex task that would greatly limit the amount that we could memorize, for this reason they help us convert these numerical sequences into understandable names, and in most cases associated with the brand, entity, person or service they serve.
What are the DNS
The DNS system was originally created to support the growth of communications via email on the ARPANET, which was the predecessor network of today’s Internet.
A decade after its creation and launch, the standards that shaped the current DNS protocol were established.
The WWW (World Wide Web) is based on the DNS protocol that allows friendly navigation for people thanks to the conversion of numbers to names that are more understandable and easy to remember.
In other words, while we use names that are more or less understandable or easy to enter in a browser, the servers prefer to convert those domain names to numerical addresses or IPs to reach the websites that we want to visit.
How DNS works
Each domain or subdomain has one or more authoritative DNS servers that publish information about that domain and the nameservers for any domains “under” it.
For example, for the wpseguro.com domain, the assigned DNS would be:
Click on image to enlarge
The hierarchy of DNS servers coincides with the hierarchy of domains.
At the top of the hierarchy are the root nameservers, which are the servers to query when looking up (resolving) a hostname. top level domain (TLDs).
Explained more graphically, it would be more or less like this:
Click on image to enlarge
If a server Primary DNS fails, the normal thing is that there is a Secondary DNS which operates independently and normally on a different network from the primary DNS to guarantee service redundancy.
That is why, in the event of a failure of the primary DNS server, the secondary DNS server comes into action and responds to all requests from websites.
And as in any self-respecting contingency plan, many Hosting providers (as is the case of ) They also have a service DNS failover (DNS failover) which is triggered by detecting that a server is not responding by propagating new DNS records to the entire system.
Check which DNS your domain points to
There are many existing services on the Internet to extract information from a domain, to know the data of the registrant and the registrar as well as the DNS to which said domain points and all this is obtained through a whois.
Whois is a TCP protocol based on request/response used to consult a database about the domain, its status and other more sensitive information (telephone, address) unless these have been hidden through services such as OwO (OvhWhoisObfuscateur from OVH).
There are several ways to find out:
- Running a whois from terminal (console).
- Running to check where each Record points to.
- Checking in DomainTools where the domain points to.
- Checking in your Client Area to Domains, My Domains, Nameservers tab.
- Checking in DNS Propagation Checker that DNS returns the query.
Of course there are many more ways to check it but I am not going to list them in this article, with those mentioned it is enough to obtain this information.
From here, and knowing where the DNS of your domain point, if they do not point correctly, the next thing is to know how to modify them.
If it is possible that a domain does not point all the DNS records to the same server, being able to separate these records by services (email, web, etc.) sending said traffic in both directions to another different server.
The records that make up a DNS are:
- First level domain (Root Domain)
- CNAME or “Canonical Name”
- Record A (Address Record)
- MX Record (Mail Exchange)
- PTR record (Pointer Record)
- NS record (Name Server Record)
- TXT record (Sender Policy Framework and DomainKeys)
- SOA Record (Start of Authority Record)
For example, name servers (NS) are DNS servers that contain information about domains.
It is possible to have a website hosted on a different server from the same Hosting provider or from another external one, simply by pointing the Record A that responds to the web and keep the mail pointed at MX record on a different server.
Assign DNS to a domain
The normal thing is that the DNS can be assigned from your Client panel (in most providers). In the case of clients, the DNS can be assigned or modified from the Client Area, Domains, My Domains, tab nameservers of the selected domain (click on the green “Active” button).
Click on image to enlarge
Once you make the change, normally the propagation of the DNS change is not immediate and you will have to wait a reasonable time for the change to be applied and your domain responds to these DNS and your website is visible.
The DNS propagation refers to the time it takes for DNS changes to be transmitted over the Internet.
As a general rule, domains with TLD it is they are the ones that take the longest to activate or apply DNS changes.
Changes usually take up to 24 hours to propagate. In the case of .es domains, changes are processed by nic.es at 02:00, 06:00, 10:00, 14:00, 18:00 and 20:00 each day.
On the other hand, domains with superior TLDs such as com, net or org tend to propagate within 4 hours of the DNS change, however in most cases they are usually already available within minutes of the change.
There can always be exceptions, so a dose of patience and calm is essential in these cases.
DNS errors how to fix them?
The DNS is a vital point of the presence and accessibility of your website. Any user trying to access your website over the Internet will not be able to do so if the DNS assigned to your domain is not working properly.
If the DNS associated with your website fails, visitors who try to access the site will receive the error message “Page not found” either “404 Page Not Found”.
It is not very common for DNS errors to occur unless they are due to incorrect assignment, which is usually the most common scenario.
The usual message when a domain has no DNS record is:
The DNS server is not responding.
Click on image to enlarge
These types of errors can be caused by connection problems from the browser with which it tries to reach or resolve a certain website.
It may be the case that the error “DNS server not found” it is due to a problem with the operation of TCP/IP or DHCP protocols (common in fiber networks) or even that the cause is your Router or Modem device.
Other causes could be associated with infected computers by viruses or malware that make it difficult to connect to the Internet.
If, for example, this happens when trying to open a site with the Firefox browser, one option that can help rule out the problem is to try opening the website from another browser, for example Google Chrome, Opera, Bing, Safari, etc.
Make sure you always use the most stable version of your usual browser to rule out that the problem is due to using an outdated or unsupported version.
Another solution that should always be tried in the face of this type of problem is cleaning or emptying the DNS cache (flush DNS), which sometimes becomes obsolete and it is necessary to empty it to renew it.
You can do it from a terminal or console on your computer by typing the command:
ipconfig /flushdns sudo service network-manager restart
Or depending on the Linux distribution too:
sudo /etc/init.d/nscd restart sudo killall -HUP mDNSResponder
In the event that the cause is the Router/Modem, first try to turn it off, wait a couple of minutes, turn it on again and after its complete activation, verify that you can access the Internet and browse normally.
If after restarting the Internet access equipment the problem persists and yet through other means, from your mobile for example, if you have Internet access and view the site that does not load from the Router/Modem, consider contacting your service provider. Internet (ISP) to resolve your issue with your device.
Also check that you can navigate connected to the Router/Modem by network cable since it is very possible that if you usually do it from your WiFi network, there is a problem of saturation of the channel assigned to your SSID of the wireless network or that there is too much distance between your Internet connection device and the wireless network point from which you are trying to connect.
If you use a firewall or Firewall, temporarily try to disable the shields that it uses and then try browsing the Internet.
You have carried out all these tests but the problem persists, don’t worry, you can always assign other DNS to your Internet access device (Router/Modem) so that it uses, for example, those of Google:
Google DNS for IPv4 (the current standard):
Google DNS for IPv6 (new standard):
- 2001:4860:4860::8888
- 2001:4860:4860::8844
You can do this type of assignment from your Router or Modem device, if it allows it in its settings:
Click on image to enlarge
Google’s DNS servers are much faster, and currently work with HTTPS offering security, as well as being free.
Conclusions
It is a proven fact that most of the incidents with domains recently purchased or transferred to a new provider are related to DNS (Nameservers).
Understanding how to detect and solve these problems is essential so that you can use your domains without errors.
Not always the DNS resolution problems of a website are related to the server or the Internet service, in many of the usual cases it is the cache of your browser that is the main cause of not displaying a certain website correctly.
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Coordinator of contents in the Blog and in Youtube.
Technical support in CyberProtector. Teacher at University
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