DNS & Glossary

A record (Address record)

The most fundamental DNS record: it maps a hostname to an IPv4 address so clients know where to send the connection.

What it stores

An A record binds a name to a 32-bit IPv4 address. When a browser resolves example.com, the A record returns the IPv4 address to connect to. Multiple A records for one name provide simple round-robin load distribution.

ZONE FILE
example.com.      300   IN   A   93.184.216.34
www.example.com.  300   IN   A   93.184.216.34

Why it matters

  • Without a correct A (or AAAA) record a hostname simply will not resolve to a server.
  • TTL on the A record controls how quickly an IP change (e.g. a failover) propagates.

Common mistakes

  • A very long TTL that delays failover when you need to move traffic quickly.
  • Pointing an A record at a private or stale IP after a migration.

How WebInspect checks this

  • The Network Inspector resolves A records, reports every returned IPv4 and its TTL, and flags a missing address record.