Truncation
The condition indicated by the TC bit when a response does not fit the allowed message size. Truncation should prompt retry over a transport that can carry the full response.
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Browse the glossaryDNS glossary — page 13
311 definitions associated with DNS.
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311 matching terms
Page 13 of 13TSIG
The common abbreviation for Transaction Signature, a shared-secret authentication mechanism for DNS messages. Current TSIG specification is RFC 8945.
Read definitionTTL
Abbreviation for Time to Live, the cache lifetime carried in each resource record. Records in one RRset should have a consistent TTL.
Read definitionTXT record
A Text record contains one or more character strings, each limited to 255 octets in wire format. TXT is used by many applications for verification, email policy, security, and metadata, with application-specific syntax.
Read definitionU-label
A Unicode form of an internationalized DNS label intended for user display and processing under IDNA rules. Its corresponding DNS-compatible A-label uses Punycode.
Read definitionUpdate prerequisite
A condition in a DNS UPDATE message that must be true before changes are applied, such as a name or RRset existing or not existing. Prerequisites support atomic conflict-aware updates.
Read definitionView
A server configuration that selects a set of zones, recursion behavior, or policy according to the client or request context. The same queried name can therefore receive different answers.
Read definitionWater torture
A common shortened name for DNS water torture, the random-subdomain attack that forces repeated cache misses and authoritative queries.
Read definitionWeight
The relative selection value among SRV records with the same priority. Higher weights should receive a proportionally larger share of selections, subject to client implementation.
Read definitionWildcard
A DNS owner name whose leftmost label is an asterisk and that can synthesize answers for certain nonexistent names below it. Wildcards do not match every descendant blindly and are constrained by existing names and closest-encloser rules.
Read definitionWildcard certificate
A TLS certificate containing a wildcard DNS name such as *.example.com. It normally matches one label at that position and does not replace DNS wildcard behavior.
Read definitionWildcard expansion
The DNS server process that synthesizes an answer from a wildcard RRset when the query name does not exist and wildcard matching rules are satisfied. The synthesized owner name is the original QNAME.
Read definitionWire format
The binary on-network representation of protocol messages, including field sizes, byte order, labels, options, and compression rules. Presentation formats such as zone files are not identical to wire format.
Read definitionXFR
A collective shorthand for DNS zone transfers, including AXFR and IXFR.
Read definitionZone
A portion of the DNS namespace managed as a unit and served authoritatively. It contains data from its apex down to, but not including, delegated child zones.
Read definitionZone apex
The top node of a zone, where its SOA and authoritative NS RRsets are stored. The apex cannot normally be a CNAME because required zone data must coexist there.
Read definitionZone cut
The boundary between a parent zone and a delegated child zone. It is marked by a parent-side delegation NS RRset and child-side authoritative zone apex.
Read definitionZone digest
A cryptographic digest over canonical zone data used to verify that a transferred or published zone is complete and unmodified. The ZONEMD record carries the digest at the zone apex.
Read definitionZone enumeration
Discovery of many or all names in a zone through transfers, NSEC walking, certificate data, search engines, logs, or other sources. DNSSEC with NSEC can make systematic walking easier.
Read definitionZone file
A text file in DNS master-file format containing directives and resource records for a zone. Authoritative data can also be stored in databases or generated dynamically.
Read definitionZone transfer
Replication of authoritative zone data using AXFR for a full copy or IXFR for changes. Transfers use TCP and should be authenticated and access-controlled.
Read definitionZone walking
Systematic enumeration of names in a DNSSEC-signed zone by following NSEC records or analyzing NSEC3 under favorable conditions. NSEC3 increases cost but does not guarantee confidentiality.
Read definitionZONEMD record
A Message Digest Over Zone Data record that provides a digest of the zone contents. It can detect corruption or incomplete distribution but does not replace DNSSEC authentication of individual answers.
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