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6

YXDomain

Name Exists When It Should Not

Core RCODERFC 2136

YXDomain (6) means a name exists in DNS when it should not – returned in response to a DNS UPDATE (RFC 2136) operation where the update prerequisite was 'name must not exist' and the name does exist. This is not seen in standard DNS queries; it is only returned in dynamic update responses.

RCODE

6

Name

YXDomain

Standard

RFC 2136

Description

YXDomain is part of the DNS UPDATE (RFC 2136) response code set and is not used for standard queries. In DNS UPDATE, clients can specify prerequisites: conditions that must be true before the update is applied. If the update includes a prerequisite 'this name must not exist' (to prevent overwriting) but the name already exists, the server returns YXDomain. This is a safeguard mechanism in dynamic DNS allowing clients to do conditional updates atomically.

Common Causes

  • –DNS UPDATE prerequisite 'name must not exist' failed – name already exists
  • –Conditional DNS update to create a new record that was already created
  • –Race condition in concurrent DNS UPDATE operations
RFC 2136 – DNS RCODE specification →