Leveraging contextual metadata communication to improve dns security

Techniques for leveraging efficient metadata communications to improve domain name system (DNS) security are described. The DNS service receives metadata associated with a client device on an encrypted channel. The DNS service applies a cryptographic hash function to the metadata to determine a first hash value and stores the first hash value in a metadata registry record with the corresponding client device metadata. The DNS service receives a DNS query containing a second hash value in an additional records section and determines that the second hash value corresponds to the first hash value. Based at least in part on the second hash value corresponding to the first hash value and the metadata associated with the client device, the DNS service resolves the DNS query and transmits a DNS response including the second hash value.