@polle I'm well aware of what Matthi was talking about. You just failed to understand my response.
ru, info, site, etc. are so-called top-level domains (TLDs; the term "extension" is incorrect in this context). A second-level domain like example.info is a subdomain of the top-level domain info (even though the term "subdomain" is not commonly used when talking about second-level domains). By adding an entry .info (with the leading dot) to the block list all subdomains of that top-level domain get blocked (like example.info, foo.example.info, some.thing.else.info, ...).
Bottom line: yes, it's possible, as already stated.