Where does a dns server look when it can't resolve a query from its zone records or cache?

When a DNS server cannot resolve a query from its zone records or cache, it typically forwards the query to a higher-level DNS server, such as a root DNS server or a server authoritative for the domain in question. The root servers provide information about the authoritative servers for top-level domains (TLDs). The DNS server then recursively queries these TLD servers until it reaches the authoritative server for the specific domain, which can then provide the requested information. If the authoritative server is unreachable or does not have the record, the query will ultimately fail.