dns4isp.cz

DomainDrift asked this domain for a TXT record at a name nobody registers, and got an answer back. A domain that answers a name that was never created is answering names in general, and that is wildcard DNS.

Wildcard DNS clusters around domain parking, dynamic DNS and catch-all hosting. It is also a real attack surface: if every invented hostname resolves, then a hostname an attacker invents resolves too, which is the ground state for subdomain takeover and for phishing hosted under a name that looks legitimate.

This is evidence of wildcard behaviour, not a proven fact. It rests on one control name: a domain could legitimately serve a TXT record at exactly that name for an unrelated reason, and a wildcard that answers address records but not TXT records would not be caught here at all. What this reading is and is not.