Pages do not open by IP address, why?

Question

Computer networks

Hello. Some time ago, I noticed that when entering the address bar of the browser (no matter what, I tried it on different ones) IP addresses instead of URLs are almost always, with rare exceptions, a server error. It didn't seem like this before, what could be the reason. Please advise or comment. Thank you.

Answer 1

Reason 1:
Starting with HTTP/1.1 (15 years ago) there was support for multi-host servers. Hundreds of sites can be located on one IP - the browser, addressing the server via IP, must add the "Host:" line to the HTTP request headers, which will allow you to understand which specific site you are going to.
Currently, multihost is the standard and the norm, and connecting via IP is rather an exception, or rather, the good will of the hoster, who, in the absence of the "Host:" field, chooses for you which of the domain names to provide by default on this IP.
Reason 2:
More and more websites are moving to HTTPS. For such servers, the correspondence of the domain name inscribed in the certificate is already critical to the "Host:" header, because Few people request, in addition to a certificate for their domain name, a certificate for an IP address, which can also change. And modern browsers, if the fields of the certificate do not match the real URL, are increasingly giving an error, protecting the user from a suspicious site.