NODATA
An informal but widely used term for an authoritative response where the queried name exists but no record of the requested type exists. The response normally has NOERROR rather than NXDOMAIN.
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Browse the glossaryDNS glossary — page 8
311 definitions associated with DNS.
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Page 8 of 13Node
A position in the DNS namespace that can own one or more resource record sets. A node can exist even without A or AAAA records.
Read definitionNon-authoritative answer
A response based on cache, recursion, forwarding, or local processing rather than the responder's authority for the queried zone. The AA bit is not set.
Read definitionNon-recursive query
A query with the RD bit clear. The server returns data it already has from authority or cache, or a referral, without being asked to perform recursion.
Read definitionNOTIFY
A DNS message that informs secondary servers that a zone may have changed so they can check the SOA serial and refresh promptly instead of waiting for the normal refresh timer.
Read definitionNS record
A Name Server record identifies an authoritative server for a zone or delegated child. Apex authoritative NS records and parent-side delegation NS records are separate RRsets.
Read definitionNS set
The group of NS records associated with a zone apex or delegation. Redundant servers should be independently reachable and consistently configured.
Read definitionNSID
The abbreviation for Name Server Identifier, an EDNS option used to identify the responding server instance behind a shared service address.
Read definitionNSLOOKUP
A long-standing command-line DNS query tool available on many operating systems. It is useful for basic testing, though dig, Resolve-DnsName, or drill often expose more protocol detail.
Read definitionNSSET
A registry or provisioning object representing the authoritative name servers and sometimes their addresses for a domain. The exact object model depends on the registry protocol or platform.
Read definitionNull MX
An MX RRset consisting of a single record with preference 0 and target dot, explicitly stating that the domain accepts no email. It is clearer than relying on failed implicit delivery.
Read definitionNXDOMAIN
The DNS RCODE indicating that the queried domain name does not exist. It applies to the name, not merely the requested record type, and can be cached as a negative answer.
Read definitionNXDOMAIN hijacking
Replacement of a legitimate NXDOMAIN response with a redirect, search page, advertisement, or other synthesized answer. It can break DNSSEC, application assumptions, and diagnostic accuracy.
Read definitionNXDOMAIN redirection
A policy or service behavior that substitutes another answer when a name should return NXDOMAIN. It may be used for captive portals or policy, but it changes standard DNS semantics.
Read definitionNXDOMAIN spike
A sudden rise in nonexistent-name responses. Causes can include typos, missing suffixes, search-list behavior, stale applications, DGAs, random-subdomain attacks, or failed service discovery.
Read definitionOpen resolver
A recursive resolver that accepts queries from arbitrary Internet clients. Open resolvers are vulnerable to abuse for reflection attacks, policy bypass, and unauthorized resource consumption.
Read definitionOPT record
A pseudo-resource-record used to carry EDNS metadata in the additional section of a DNS message. Its class field advertises UDP payload size, while TTL bits carry extended RCODE, version, and flags.
Read definitionOption 119
The Domain Search option, which distributes an ordered list of DNS search suffixes using DNS name compression encoding. It is distinct from option 15, which carries a single domain name.
Read definitionOption 81
The Client FQDN option, used to communicate a client's FQDN and dynamic DNS update preferences. It supports coordinated ownership of A and PTR updates.
Read definitionOrphaned record
A DNS or IPAM object whose intended owner, target, device, or application no longer exists or cannot be identified. Orphans create security risk and complicate address reclamation.
Read definitionOut-of-bailiwick
A name outside the relevant zone or delegation boundary. An out-of-bailiwick child name-server name normally does not require parent glue because it can be resolved through its own delegation path.
Read definitionOwner name
The domain name at which a resource record set is stored. It is the left-hand name in zone-file presentation format.
Read definitionParent zone
The zone immediately above a delegated child zone. It publishes the delegation NS RRset, optional DS records, and any required glue.
Read definitionPassive DNS
A system that collects and indexes observed DNS query or response data over time without actively probing every name. It supports investigations, threat intelligence, asset discovery, and historical correlation.
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