Hello to the rockylinux community (I write in english, but when German is fine, answer in German 
),
I have determined a problem with the Rocky 10.0 Boot ISO file. I can´t install it anymore because it can´t setup the repositories. First I think there is a failure in my network or something like that but now I have tested it on a host where it works before (Rocky 10.1 was released??).
Is this a expected behavior or not?
This is the expected behavior. You have to download the 10.1 boot iso and burn it to usb.
So when 10.2 comes out you will have to download that to do new installs.
This behavior is expected. We do not keep the older releases accessible in our mirror list system. If you insist on installing from the boot ISO, you will need to configure it manually or consider using kickstarts that configure the repository locations.
The only way around this is to use the DVD ISO that contains BaseOS and AppStream.
Yes, 10.1 was released in November. Releases happen just about every 6 months, usually in May/June or November/December. 10.0 is no longer supported.
Another alternative is to use the minimal iso. That will get you a basic system installed, and then you can build on that later using normal dnf install commands for anything additional.
I have tried to configure it manually (because there outside are a lot of mirrors they still hold the 10.0 repos) but it does not work because I don´t know the correct URL format…
The url format is clearly shown in the screenshot provided by @label or alternatively, if you are unsure of how to use the boot.iso, then use the minimal or dvd iso’s instead.
