Root hints
A bootstrap list of root name server names and addresses used by a full resolver to begin iterative resolution. Resolvers update their working root-server information from DNS responses.
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Browse the glossaryDNS glossary — page 11
311 definitions associated with DNS.
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Page 11 of 13Root label
The zero-length label at the top of the DNS hierarchy. It is shown as the trailing dot in an absolute domain name and as a single dot when written alone.
Read definitionRoot name server
An authoritative server for the DNS root zone. The named root-server identities are served by many anycast instances distributed worldwide.
Read definitionRoot priming
The process by which a recursive resolver queries a root server using hints to obtain the current root NS RRset and associated addresses.
Read definitionRoot zone
The zone at the top of the DNS hierarchy, represented by a single dot. It delegates top-level domains and contains DNSSEC trust-chain data for signed delegations.
Read definitionRPZ
Abbreviation for Response Policy Zone. It is used by recursive resolvers to apply distributed DNS response policies.
Read definitionRRL
Common abbreviation for DNS Response Rate Limiting. It reduces the volume of repeated spoofable responses while trying to preserve legitimate service.
Read definitionRRset
Common abbreviation for Resource Record Set, the records sharing owner name, class, and type.
Read definitionRRTYPE
The numeric resource-record type code identifying the format and meaning of RDATA, such as A=1, AAAA=28, or HTTPS=65. IANA maintains the registry.
Read definitionScavenging
Automatic removal of DNS records considered stale according to timestamp and aging settings. In Microsoft DNS, both zone aging and server scavenging schedules must be configured correctly.
Read definitionSearch suffix
A domain suffix appended by a client to relative names during resolution. Multiple suffixes form a search list whose order and qualification rules can create unexpected queries.
Read definitionSecondary DNS server
An authoritative server that obtains zone data from another authoritative source, traditionally through AXFR or IXFR. It can answer clients independently and is not inherently less authoritative than the primary.
Read definitionSecondary zone
A read-only authoritative copy of a zone obtained from a primary or another secondary. It refreshes based on SOA timing, NOTIFY, and transfer behavior.
Read definitionSecure dynamic update
A DNS UPDATE process authenticated and authorized so only approved clients or services can change records. Common mechanisms include TSIG, GSS-TSIG, SIG(0), and platform identity controls.
Read definitionSerial number
The SOA field used by secondary servers to determine whether zone data has changed. Serial arithmetic wraps modulo 2^32 and should follow RFC 1982.
Read definitionSERVFAIL
RCODE 2, indicating that the server failed to complete the operation. Causes include upstream timeout, DNSSEC validation failure, lame delegation, expired secondary zone, policy, or internal error.
Read definitionService binding
A framework using SVCB and HTTPS records to describe alternative endpoints and connection parameters for a service. It can advertise protocols, ports, address hints, and security-related parameters.
Read definitionService discovery
The process of locating service endpoints and parameters through DNS records or related naming conventions. SRV, NAPTR, SVCB, HTTPS, and service-specific records can participate.
Read definitionService mode
The SVCB or HTTPS record form that directly describes connection parameters for a service endpoint. It uses a nonzero priority and can contain service parameters.
Read definitionSlave server
An older term for a secondary authoritative DNS server. Current standards terminology prefers secondary because it is more precise and neutral.
Read definitionSOA minimum
The final field of the SOA record. Historically it had multiple interpretations; current negative-caching rules use it with the SOA TTL to determine the negative TTL.
Read definitionSOA record
The Start of Authority record identifies key zone parameters including MNAME, RNAME, serial, refresh, retry, expire, and minimum fields. Every authoritative zone has an SOA at its apex.
Read definitionSource port randomization
Use of unpredictable UDP source ports in recursive DNS queries to increase the entropy an off-path attacker must guess when forging a response.
Read definitionSpecial-use domain
A domain name reserved by an RFC for special behavior, such as localhost, invalid, test, or onion. Applications and resolvers may treat such names differently from ordinary public DNS names.
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