Glossary

A Record

Maps a domain name to an IPv4 address

An A record (Address record) is a DNS record type that maps a domain name to an IPv4 address, allowing browsers and other clients to locate the server hosting that domain.

What is an A Record?

An A record, short for Address record, is one of the most fundamental building blocks of the Domain Name System. Its sole purpose is to point a human-readable domain name — such as example.com — to a machine-readable IPv4 address, such as 93.184.216.34. Without A records, the internet as we know it would not function, because computers communicate using numeric IP addresses rather than domain names.

When you type a URL into your browser, a DNS resolver queries the authoritative name server for that domain and retrieves its A record. The resolver then returns that IP address to your browser, which opens a connection to the web server at that address. A single domain can have multiple A records pointing to different IP addresses, which is a common technique for load balancing and redundancy.

A records are set inside your DNS zone file and managed through your domain registrar or DNS hosting provider. They are simple in structure: a hostname, a TTL (Time to Live) value, the record type "A", and the target IPv4 address.

How Does an A Record Work?

When a user requests a domain, their device first checks its local DNS cache. If no cached result is found, the query travels to a recursive DNS resolver, typically provided by the user's ISP or a public resolver like Google (8.8.8.8) or Cloudflare (1.1.1.1). The resolver then contacts the root name servers, which direct it to the correct top-level domain (TLD) name server, and finally to the domain's authoritative name server.

The authoritative name server holds the zone file for that domain and returns the A record — the IPv4 address — back to the resolver. The resolver caches that result for the duration specified by the TTL and returns the IP to the client. The browser then initiates a TCP connection to that IP address, completing the lookup process. This entire chain typically happens in milliseconds, making the internet feel instantaneous to end users.

Multiple A records for the same hostname enable round-robin DNS, a simple form of load distribution where different clients receive different IP addresses in rotation.

How to Check an A Record

You can instantly look up the A record for any domain using the free A Record Lookup tool at nslookup.net/tools/a-record-lookup. Simply enter the domain name and the tool queries live DNS servers to return the current A record values, including all IP addresses and their TTL values. This is especially useful when troubleshooting DNS propagation, verifying a recent change, or investigating an unfamiliar domain. No installation or login is required.

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Frequently Asked Questions

What is the difference between an A record and a CNAME record?

An A record maps a domain directly to an IPv4 address, while a CNAME record maps a domain to another domain name (an alias). A records are used for root domains and direct IP assignments, whereas CNAMEs are typically used for subdomains that should follow another hostname. You cannot use a CNAME at the apex (root) of a domain.

Can a domain have more than one A record?

Yes, a domain can have multiple A records, each pointing to a different IPv4 address. This is called round-robin DNS and is used for basic load balancing, where DNS resolvers rotate through the available IP addresses. It also provides some redundancy, though it is not a replacement for a proper load balancer.

How long does it take for an A record change to propagate?

Propagation time depends on the TTL value set on the record. If the TTL is 3600 seconds (one hour), resolvers around the world may cache the old value for up to an hour after you make a change. Lowering the TTL before making a planned change can reduce propagation delays significantly.

What happens if a domain has no A record?

If a domain has no A record, DNS resolvers will be unable to return an IP address for it, and any attempt to load the domain in a browser will fail with a DNS resolution error. The domain may still have other record types (such as MX for email), but web traffic will not work without an A record or equivalent.