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Is it possible to use A Records?
I want to use the URL with a gameserver.
That depends on what you mean by "use" A records.
Do you want to point your domain name to your account with an A record in your own nameservers? That's possible, just follow this article: https://infinityfree.net/support/find-your-ip/
As for creating A records in our nameservers, that's not possible.