Terms explained

Plain-language definitions for technical terms used by this tool.

DNS: The distributed system that maps domain names to records such as IP addresses and mail servers.
TTL: Time To Live: how long a DNS answer or cached result may be reused.
A / AAAA record: DNS records mapping a name to an IPv4 or IPv6 address.
CNAME: A DNS alias pointing one hostname to another hostname.
Port: A numbered network endpoint used to reach a particular service on a host.
Latency: Round-trip delay, usually measured in milliseconds; lower is faster.
HTTP header: Metadata sent with an HTTP request or response, separate from its body.
WebSocket: A persistent, two-way connection between a client and server after an HTTP upgrade.

HTTP Tester & API Client