DNS Lookup
Query DNS records for any domain. Returns A (IPv4), AAAA (IPv6), and PTR (reverse DNS) records.
Understanding DNS Record Types
A Record A
An A record (Address record) maps a domain name to an IPv4 address.
This is the most fundamental DNS record type -- when you type a URL in your browser,
the A record is what resolves the domain to the server's IP address (e.g.
example.com → 93.184.216.34). A domain can have
multiple A records for load balancing or redundancy.
AAAA Record AAAA
An AAAA record (quad-A record) is the IPv6 equivalent of the A record.
It maps a domain name to a 128-bit IPv6 address (e.g.
example.com → 2606:2800:220:1:248:1893:25c8:1946).
As the internet transitions to IPv6, AAAA records are becoming increasingly important.
Not all domains have AAAA records yet.
PTR Record PTR
A PTR record (Pointer record) performs reverse DNS lookup -- it maps
an IP address back to a hostname. PTR records are commonly used for email server
verification (reverse DNS check), network diagnostics, and logging. They are stored
in special in-addr.arpa (IPv4) or ip6.arpa (IPv6) zones.
How DNS Works
The Domain Name System (DNS) is the internet's phonebook. When you visit a website,
your device queries a chain of DNS servers: first the recursive resolver
(usually your ISP or a service like 8.8.8.8), then the root
nameservers, the TLD nameservers (.com, .org, etc.), and
finally the domain's authoritative nameserver which holds the actual
records. Results are cached at each level using TTL (Time To Live) values.
TTL (Time To Live)
Every DNS record includes a TTL value in seconds that tells resolvers
how long to cache the result. A TTL of 3600 means the record is cached
for one hour. Lower TTL values (e.g. 300) allow faster propagation of
changes but increase query load. Higher values (e.g. 86400) reduce
load but mean changes take longer to propagate globally.
Common Use Cases
DNS lookups are essential for debugging connectivity issues, verifying DNS propagation after making changes, checking mail server configuration (MX + PTR records), and investigating domain infrastructure. Developers frequently use DNS lookups when setting up new services, migrating servers, or troubleshooting deployment issues.