AAAA record

AAAA record
Ruurtjan Pul · CC BY 4.0 · source
Name	AAAA record
Type	DNS resource record
Purpose	Maps a hostname to a 128-bit IPv6 address
Introduced	1999
Related	A record, DNSSEC, DNS64, IPv6, DNS resolver

AAAA record

An AAAA record associates a domain name with an IPv6 address, enabling name-to-address mapping for IPv6-capable hosts and services. It complements legacy address mapping mechanisms and interacts with protocols and systems that include Internet Protocol version 6, Domain Name System, DNSSEC, DNS resolver, and network stacks implemented in projects such as Linux kernel, Windows NT, FreeBSD, and BIND. Designed as part of the transition from Internet Protocol version 4 to Internet Protocol version 6, it is fundamental to modern Internet routing and service discovery.

Overview

An AAAA record stores a 128-bit address for a resource name in the Domain Name System, enabling clients to locate endpoints running on IPv6. Its formal specification appears in standards developed by the Internet Engineering Task Force and working groups like the DNS Extensions (dnsext) and IPv6 Working Group. Administrators add AAAA records in zone files managed by servers such as BIND, Knot DNS, PowerDNS, or cloud services from vendors like Amazon Web Services, Google Cloud Platform, and Microsoft Azure. Resolving AAAA records involves interactions among recursive resolvers, authoritative servers, and validating resolvers that may implement DNSSEC and privacy-enhancing extensions.

Format and Syntax

An AAAA record is represented in zone files with a label, TTL, class, type, and a 128-bit IPv6 literal in standard text representation. Examples use notation standardized by Internet Engineering Task Force documents and commonly accepted in implementations including ISC BIND, Unbound, and dnsmasq. The textual form accepts compressed and expanded IPv6 address formats defined by Request for Comments 4291 conventions and follows general DNS zone syntax used in utilities such as dig, host, and nslookup. Zone management interfaces provided by control panels from cPanel, Plesk, and hosted registrars adopt this syntax while offering validation and propagation features.

Usage and Resolution Behavior

Clients perform AAAA queries using recursive resolution libraries implemented in software stacks such as glibc, musl libc, Android (operating system), and iOS. Resolvers may issue AAAA and A queries in parallel or prefer one depending on system policy and features like Happy Eyeballs implemented by Google Chrome, Mozilla Firefox, and application libraries like libcurl. When networks lack native IPv6 reachability, middleboxes such as NAT64 gateways and translation services like DNS64 synthesize addresses to enable connectivity. Authoritative responses are provided by name servers running NSD, PowerDNS Authoritative Server, or cloud DNS offerings operated by Cloudflare and Akamai.

Comparison with A Record

The AAAA record parallels the A record but stores a 128-bit IPv6 address instead of a 32-bit IPv4 address. While A records integrate with legacy address allocation frameworks maintained by Internet Assigned Numbers Authority and regional registries like ARIN, RIPE NCC, and APNIC, AAAA records correspond to IPv6 allocations tracked by the same organizations. Client selection logic between AAAA and A interacts with algorithms and specifications discussed in RFC 6724 and implementations in operating systems such as Windows Server, macOS, and Ubuntu (operating system). Transitional mechanisms—examples include Dual-stack deployments and tunneling protocols promoted by Hurricane Electric and 6to4—influence whether AAAA or A responses are effective for end-to-end connectivity.

Deployment Considerations and Best Practices

Operators should ensure authoritative name servers, resolvers, and edge devices have IPv6-capable configurations consistent with guidance from IETF working groups and regional convergence plans by bodies like European Commission initiatives. Best practices include publishing both AAAA and A records for dual-stack services, validating reverse mappings via PTR records delegated through organizations such as ARIN and RIPE NCC, and testing with tools from RIPE NCC and network measurement projects like M-Lab. Infrastructure components—load balancers from F5 Networks, NGINX, and cloud LB offerings—must be configured for IPv6 health checks. Administrators should monitor propagation across recursive resolvers operated by providers including Google Public DNS, Cloudflare DNS, and OpenDNS.

Security and Privacy Implications

AAAA records participate in DNS attack surfaces including cache poisoning, spoofing, and enumeration when combined with orphaned AAAA entries. Mitigations involve DNSSEC signing with key management practices from IETF and operational guidance by organizations like ICANN. Privacy concerns arise from IPv6 address stability and client tracking; protocols such as IPv6 privacy extensions and ephemeral addressing described in RFC 4941 are relevant, as are platform-specific implementations in Android (operating system) and Windows 10. Resolver-side privacy mechanisms, including Query Name Minimization influenced by IETF drafts and encrypted transport protocols like DNS over HTTPS and DNS over TLS, reduce exposure of AAAA queries to eavesdroppers and intermediate networks controlled by entities such as large ISPs and content delivery networks like Akamai.

Category:Internet standards