DNS A vs AAAA records
In-Depth Technical Comparison & Architecture Guide
DNS routes client sessions over IPv4 using A records, and over IPv6 using AAAA records. We compare their network features.
Quick Reference Matrix
| Metric | A Record | AAAA Record |
|---|---|---|
| Address Format | 32-bit IPv4 (e.g., 192.0.2.1) | 128-bit IPv6 (e.g., 2001:db8::1) |
| Bit Size | 32 bits | 128 bits |
| Target Type | IPv4 host mapping | IPv6 host mapping |
Technology Overview
A records resolve hostnames to 32-bit IPv4 addresses. AAAA records resolve hostnames to 128-bit IPv6 addresses, supporting modern dual-stack networks.
Dual-Stack Name Resolution
Modern web hosts support dual-stack configurations, declaring both A and AAAA records. Clients query both and choose the optimal routing path.
A Record Advantages & Disadvantages
Advantages / Pros
- Universal compatibility
- Simple addressing formats
Disadvantages / Cons
- IPv4 address exhaustion limits growth
AAAA Record Advantages & Disadvantages
Advantages / Pros
- Massive address spaces
- No NAT translation required
Disadvantages / Cons
- Slower network adoption rates
Real-World Use Cases
A Record
Standard client hosting
Resolving names to traditional IPv4 servers.
AAAA Record
Modern IPv6 routing
Direct host-to-host routing on dual-stack networks.
Developer Recommendation
Configure both A and AAAA records on public web domains to support all client connection formats.
Frequently Asked Questions
- What does AAAA stand for?
- The four As represent the quadrupled size of IPv6 addresses (128 bits) compared to IPv4 (32 bits).
Launch Interactive Developer Tools
Put these concepts into practice. Test, format, serialize, or analyze your inputs locally with these secure, browser-only utilities: