EDNS Client Subnet
The full name of ECS, an option that shares a truncated client network prefix with upstream authoritative systems. Operators should understand its privacy, caching, and traffic-steering effects.
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311 definitions associated with DNS.
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311 matching terms
Page 5 of 13EDNS Cookie option
The EDNS option used to transport DNS Cookies between client and server. It helps verify return reachability and harden UDP exchanges against spoofing.
Read definitionEDNS Keepalive
An EDNS option used with DNS over TCP to signal a desired idle timeout for a persistent connection. It can reduce repeated connection setup while allowing servers to control resource use.
Read definitionEDNS option
A typed extension carried inside the OPT pseudo-record. Registered options include NSID, Cookies, Client Subnet, Padding, Extended DNS Error, TCP Keepalive, Chain, and multiple experimental or specialized functions.
Read definitionEDNS Padding
An EDNS option that adds padding bytes to DNS messages so packet sizes reveal less information about the queried name or response. It is especially useful with encrypted DNS transports.
Read definitionEDNS version
A field in the OPT record that identifies the EDNS version. EDNS version 0 is the deployed standard; unsupported versions normally produce BADVERS.
Read definitionENUM
A system for mapping E.164 telephone numbers into DNS names and retrieving service information through NAPTR records. Digits are reversed and represented beneath e164.arpa.
Read definitionEXPIRE
The SOA field that tells a secondary how long it may continue serving a zone without successfully refreshing from an upstream source. After the interval, the zone becomes expired and should no longer be served authoritatively.
Read definitionExternal DNS
Authoritative DNS intended to answer public or partner-facing queries, typically with recursion disabled and tightly controlled zone transfer and update access. It is often separated from internal DNS by servers, views, networks, or accounts.
Read definitionFast flux
Rapidly changing DNS address records that map a malicious domain to many compromised hosts, often with low TTLs and distributed name servers. It increases resilience for phishing, malware, or proxy infrastructure.
Read definitionFCrDNS
Forward-confirmed reverse DNS, a check in which an address resolves to a PTR name and that name resolves back to the original address. It can be a useful signal but is not proof of identity or authorization.
Read definitionFingerprint
A pattern of observable behavior used to infer device type, software, or activity. DHCP option order, DNS query patterns, EDNS support, and TTL behavior can contribute to a fingerprint.
Read definitionFlattening
The process of resolving an alias target within an authoritative platform and returning terminal records to the requester. It is often applied to apex aliases and can obscure target TTL or failure behavior.
Read definitionForward first
A resolver policy that tries configured forwarders first and performs its own iterative resolution if forwarding fails. The fallback can bypass central policy or security controls if not intentionally designed.
Read definitionForward lookup
Resolution from a name to data, most commonly A or AAAA addresses. Forward zones are contrasted with reverse zones that map addresses back to names.
Read definitionForward only
A resolver policy that uses only configured forwarders for selected or all queries and does not fall back to independent recursion. Failure of all forwarders results in query failure.
Read definitionForward zone
A configuration that forwards queries for a selected namespace to designated upstream resolvers. It is a resolver configuration object and is not necessarily an authoritative DNS zone.
Read definitionForward-confirmed reverse DNS
The expanded form of FCrDNS. It validates that a PTR result has a forward address mapping back to the original address.
Read definitionForwarder
A resolver that sends a query to another resolver instead of performing the complete iterative resolution itself. Forwarders can centralize policy, cache, logging, Internet access, or encrypted transport.
Read definitionForwarding resolver
A resolver that relies primarily or entirely on one or more upstream resolvers rather than directly walking the DNS hierarchy. It may still cache responses and enforce local policy.
Read definitionFQDN
Fully Qualified Domain Name, a name that identifies its complete position in the DNS hierarchy. In strict presentation form it includes the trailing root dot, though common usage often omits the visible dot.
Read definitionFragmentation
Splitting an IP packet into smaller fragments because it exceeds a path or link MTU. Fragmented DNS UDP responses are more likely to be lost, filtered, or abused, so modern DNS operations aim to avoid them.
Read definitionFreeze
A product operation that temporarily stops dynamic modifications to a zone so its backing file or data can be edited safely. In BIND, thaw resumes normal dynamic update processing.
Read definitionFull resolver
A resolver capable of performing iterative queries from the DNS root toward the authoritative servers needed to answer a question. It contrasts with a stub resolver that depends on another resolver.
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