Unfortunately, sometimes when trying to access a website or even when connecting to the Internet, many users see an error message that says that the DNS server address cannot be resolved. Not every user knows what to do in such a situation. But, as it turns out, there is no particular reason for concern, since the failure is fixed quite simply.
Why can't resolve the server's DNS address?
As you know, DNS servers are the means of interpreting Internet resource addresses from a numeric expression to a character expression, in which letters, numbers, and special characters can be used in addresses.

So what is the reason why sometimes the system fails to resolve the DNS server address? As a rule, this may be due to exposure to viruses, removal of anti-virusproduct (often this is observed with Avast), "gathering" of network settings or incorrectly set parameters. Let's look at a few typical situations with possible troubleshooting methods.
Error "Unable to resolve the DNS address of the server": what to do first?
First of all, you should check your computer for viruses. You never know, maybe this is the reason. But you need to use some third-party product for this, and not a regular scanner.
But even if no viruses are found, the system may still display a message stating that the DNS server address cannot be resolved. So, the problem is just in the network settings. Therefore, initially you need to check whether such a message is issued only when accessing a particular site or in general to all pages when trying to open them. If possible, it is better to check access from several devices, say, from a desktop computer, laptop and smartphone. If only one site is not responding, it may just be undergoing technical work. If access is blocked for all resources, the problem may be caused by the provider. But if access is possible from any one device, the reason that the system cannot resolve the DNS server address should be looked for precisely in the set network parameters.
Checking DNS client status
On a desktop computer or laptop, first check the status of the DNS client.

For this, the services section is used, which can be entered through computer administration, but it is easier to immediately enter the services.msc command in the Run console Win + R). Here you need to find the corresponding line and look at the installed startup type. The parameter must correspond to automatic start. If the value is different, you should call the properties menu and change it.
Control the settings of the protocol used
If this solution does not work, you need to use the network settings, in particular the default protocol used (usually IPv4).
Find it in the section for changing network adapter settings, press the properties button and check what is set in the preferred and alternative DNS server fields. Perhaps, as is often the case, parameters are automatically set.

You can try to change them to the values offered by the Google Public DNS service. Here in one line you should set four eights, and in the other - two eights and two fours. In principle, which combination will be used for each type of server does not play a special role.
Clear DNS cache and restore settings
Finally, if the error message that it still can't resolve the DNS server address reappears, you can simply clear the DNS cache or even reset the settings.

The cache uses the command line launched fromadmin rights, in which ipconfig / flushdns is written. You can, of course, add commands to re-register the configuration, but in most cases, the usual cleaning will suffice.

In principle, if you are too lazy to do such things, you can download and install a special Microsoft Fix It application on your computer! (by the way, it was designed specifically to fix Internet connection errors). It is enough just to activate the utility and wait for the end of the scanning process and troubleshooting (the processes proceed completely automatically without user intervention).
Instead of afterword
In general, the proposed solutions allow you to eliminate quite a lot of problems related to DNS settings. They apply equally well not only to the error described above, which has the 105th code, but also to some other failures, when problems of this nature are cited as the main reason for the lack of communication or access to resources. But if you approach the troubleshooting from a practical point of view, many users who are not particularly versed in network settings can be advised to use the "native" program from Microsoft, especially since no one knows Windows systems better than they themselves. But in principle, if you still have at least some idea about the system settings, it is better to turn to solutions without using an automatic fixer.