Wildcard DNS record
A wildcard DNS record uses an asterisk label, such as *.example.com, to answer queries for any subdomain without its own explicit record, a mechanism first described in RFC 1034 and later clarified in RFC 4592. It's commonly used to point every subdomain of a domain at the same server, for example routing arbitrary customer subdomains on a SaaS platform to one load balancer without adding a DNS record per customer. The tradeoff is that a wildcard can silently resolve typos and never-registered subdomains, which helps attackers probing for subdomain takeovers and can mask the fact that a subdomain was never actually provisioned. A wildcard only applies when no more specific record exists for the queried name; an explicit record for a subdomain always takes precedence. AdminKit's DNS lookup tool shows exactly which record answered a query, making wildcard coverage easy to confirm.
By AdminKit team, Netbase JSC · Updated