First some technical constraints:
The host part (the part between https:// (or http://) and the next slash) is not case sensitive. In this part you can mix uppercase and lowercase letters as you like. So, for your examples this means, that both of these two versions will always work, and you will always reach the very same resource:
www.deutscherVerlag.com
www.deutscherverlag.com
Anything after this first single slash could be case sensitive. If it is case sensitive or not depends on the operation system of the server and on the server software. So, for some URLs it is possible to replace letters with their uppercase/lowercase counterpart, and for some URLs such a replacement makes the URL invalid.
So be careful with this part of your example. It is very likely, that only one of them will work while the other version might fail. It is also possible, that both of them are valid but refer to two different resources.1
Beispiel
beispiel
The international standard is to write the host part completely in lowercase letters. The rest has to be written as defined by the provider of the resources.
This international standard is also used for resources in German language. But some companies have defined a corporate identity where a specific capitalization is used also for their URL.
Here are some examples:
But as far as I can tell these are just exceptions. German native speakers are used to URLs in all lowercase, and most of them just don't care.
1 Something similar is true for e-mail addresses: The part behind the @ sign is the host part which is case insensitive. The part before this symbol depends on settings of the server. On some servers this part is case sensitive, on some it is not. ([email protected] and [email protected] might be the addresses of two different people, they might be the same address, or it could be that only one of them works.)