A/AAAA Address Lookup Tool
A & AAAA Lookup is a foundational DNS tool used to find the IP addresses (both IPv4 and IPv6) that a domain or subdomain points to. It is essential for verifying server connectivity and load balancing.
Identify the IP addresses associated with any domain hostname. Check both IPv4 (A) and IPv6 (AAAA) records in one search.
Type a domain to check DNS records.
What are A and AAAA Records?
At the heart of every domain name resolution are the A and AAAA records. These records serve as the definitive map between a human-readable domain name (like example.com) and the numerical IP addresses that computers use to identify each other on the network.
The A record (Address record) maps a domain to an IPv4 address (e.g., 192.168.1.1). The AAAA record (Quad-A record) performs the exact same function but maps to the much larger IPv6 address space (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). Together, they ensure that your website is accessible to everyone, regardless of which version of the Internet Protocol they are using.
The Evolution of IP Addressing
A Record (IPv4)
IPv4 has been the standard since the early days of the internet. It uses 32-bit addresses, allowing for about 4.3 billion unique combinations. While this seemed vast in the 1980s, the explosion of connected devices has led to "IPv4 exhaustion."
AAAA Record (IPv6)
IPv6 was designed to replace IPv4. It uses 128-bit addresses, providing an astronomical 340 undecillion addresses. AAAA records allow for more efficient routing and direct end-to-end connectivity without NAT.
Load Balancing with Multiple Records
Did you know a single domain can have multiple A or AAAA records? This technique is known as Round-Robin DNS. When a user requests your domain, the DNS server returns the entire list of IP addresses, often in a different order each time.
This allows traffic to be distributed across multiple servers, preventing any single machine from becoming a bottleneck. Modern Content Delivery Networks (CDNs) take this further by using Anycast, where multiple geographically dispersed servers share the same IP address, ensuring users are always routed to the closest available node.
Understanding TTL and Caching
Every DNS record comes with a TTL (Time to Live) value. This is a timer (usually in seconds) that tells DNS resolvers how long they can "cache" or remember the record before they must ask the authoritative server for a fresh copy.
Short TTL (e.g., 300s)
Allows for fast updates and failover. Monitor your cache expiry with our TTL Checker.
Long TTL (e.g., 86400s)
Reduces DNS traffic and improves speed, but changes take longer to propagate globally.
The Myth of "Instant" DNS Changes
When you update an A or AAAA record, it isn"t instantly visible to everyone. This is because thousands of intermediate servers (your ISP, Google, Cloudflare) have already cached the old IP address.
Propagation is the process of these caches expiring and fetching the new data. While some services offer "Instant DNS," the true propagation time depends entirely on the TTL of your old record. Always lower your TTL 24 hours before a planned server migration!
Frequently Asked Questions
Can I have both A and AAAA records?
Absolutely! This is called "Dual-Stack" networking. Modern browsers will prioritize the AAAA (IPv6) record if available, falling back to the A (IPv4) record if the user"s network doesn"t support IPv6.
What is the difference between A and CNAME?
An A record maps to a numerical IP address. A CNAME record maps one domain name to another (an alias). Root domains (like example.com) usually must use A records, while subdomains (like www) often use CNAMEs.
How many A records can I have?
Technical limits vary by provider, but typically you can have dozens of A records for a single name. This is common for massive sites like Facebook or Google to handle global traffic.
Dual-Stack is the Standard
With the global push for IPv6 adoption, having both A and AAAA records is considered a best practice for modern web performance and accessibility. Use this tool to ensure your domain is correctly mapped for the next generation of the internet.