AAAA record
An IPv6 Address record maps a domain name to a 128-bit IPv6 address. The name is pronounced "quad A".
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Browse the glossaryIPv6 glossary
46 definitions associated with IPv6.
Browse IPv6 definitions
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Duplicate Address Detection, the Neighbor Discovery procedure a node uses before assigning an IPv6 unicast address to an interface. It helps detect another node already using the same address on the link.
Read definitionDHCPv6
The DHCP protocol for IPv6. It uses UDP ports 546 and 547, DUID-based identities, identity associations, and messages such as SOLICIT, ADVERTISE, REQUEST, and REPLY.
Read definitionDNS64
A resolver function that synthesizes AAAA records from IPv4 A records using a configured IPv6 prefix, allowing IPv6-only clients to reach IPv4 services through NAT64.
Read definitionEUI-64
A 64-bit Extended Unique Identifier format. Modified EUI-64 was historically used to form IPv6 interface identifiers from MAC addresses, though modern systems often use privacy or stable-random identifiers instead.
Read definitionGlobal scope
The address scope intended for reachability beyond the local link, subject to routing and policy. Global unicast addresses normally come from 2000::/3, though the concept of scope is broader than that allocation block.
Read definitionGlobal unicast address (GUA)
An IPv6 unicast address designed for global routing, generally allocated from 2000::/3 at present. A GUA can still be filtered or used only internally depending on routing policy.
Read definitionHappy Eyeballs
A client connection strategy that quickly races or sequences IPv6 and IPv4 attempts so users are not delayed by a broken path for one family. It affects how A and AAAA answers translate into observed connections.
Read definitionICMPv6
The IPv6 control protocol used for errors, diagnostics, Neighbor Discovery, Router Advertisements, multicast listener functions, and other essential operations. Blocking it broadly can break IPv6.
Read definitionIID
Interface Identifier, the lower-order portion of an IPv6 unicast address used to identify an interface within a subnet prefix. Modern IID generation may use stable-random or temporary privacy methods rather than embedding a MAC address.
Read definitionIp6.arpa
The DNS reverse-mapping domain for IPv6. Each hexadecimal nibble of the 128-bit address is reversed as a label beneath ip6.arpa.
Read definitionIPv4-mapped IPv6 address
An IPv6 representation of an IPv4 address in ::ffff:0:0/96, commonly used by APIs and dual-stack software. It does not by itself provide network translation.
Read definitionIPv6 address scope
The reachability boundary associated with an IPv6 address, such as interface-local, link-local, or global. Scope identifiers may be required when using link-local addresses on a multi-interface host.
Read definitionIPv6 Router Advertisement
An ICMPv6 message sent by routers to announce prefixes, default-router information, lifetimes, MTU, flags, and optional configuration such as recursive DNS. Hosts use it for on-link determination and often for SLAAC.
Read definitionIPv6 subnet
An on-link IPv6 prefix, conventionally /64 for ordinary LANs that use SLAAC and Neighbor Discovery. Different prefix lengths are possible for specific link types and designs.
Read definitionIPv6-only network
A network where endpoints are not assigned native IPv4 addresses. Access to IPv4-only services may be provided through NAT64, DNS64, 464XLAT, proxies, or application gateways.
Read definitionLLA
Common abbreviation for IPv6 link-local address. Every IPv6-enabled interface generally has one, and routing protocols and Neighbor Discovery frequently use it.
Read definitionManaged address configuration flag (M flag)
A Router Advertisement flag indicating that hosts should use DHCPv6 for stateful address configuration. Host behavior can vary by operating system and network policy.
Read definitionNA
Neighbor Advertisement, an ICMPv6 Neighbor Discovery message used to answer Neighbor Solicitations, announce address or link-layer changes, and support reachability and duplicate-address procedures.
Read definitionNAT64
A translation mechanism that lets IPv6 clients communicate with IPv4 servers by mapping between an IPv6 prefix and IPv4 addresses. DNS64 is commonly paired with it to synthesize reachable AAAA answers.
Read definitionNeighbor Advertisement
The expanded name of the ICMPv6 NA message. It carries target and link-layer information and can be solicited or unsolicited.
Read definitionNeighbor cache
A per-interface table mapping IPv6 neighbors to link-layer addresses and reachability states. It is the IPv6 counterpart to the IPv4 ARP cache, with richer state tracking.
Read definitionNeighbor Discovery (ND)
The ICMPv6 framework used for router discovery, prefix discovery, address resolution, neighbor reachability, redirects, and Duplicate Address Detection. It replaces ARP and several IPv4 control mechanisms.
Read definitionNeighbor Solicitation
An ICMPv6 message used to resolve a neighbor's link-layer address, verify reachability, or perform Duplicate Address Detection. It is commonly abbreviated NS.
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