`dnsDomainIs()`

True if host ends with domain. A plain string suffix comparison, no DNS lookup.

dnsDomainIs(host, domain)  →  boolean

Because it is a plain suffix test, the domain must start with a dot: dnsDomainIs(host, "corp.example") also matches evilcorp.example. Write dnsDomainIs(host, ".corp.example") and, if the apex itself matters, add host == "corp.example".

Example

if (dnsDomainIs(host, ".corp.example") || host == "corp.example") {
  return "DIRECT";
}

Engine notes

Engine	Behaviour	Source
chromium	Plain suffix comparison (host.length >= domain.length && host ends with domain).	code, verified 2026-10-04 services/proxy_resolver/pac_js_library.h@cb6eb0e7

Availability

Derived from each engine's vendored helper library plus its native bindings (see engines).
Function	chromium <=51	chromium >=52	firefox all	pacparser <=1.4.6	pacparser 1.5.0	pacparser >=1.5.1	reference all
`dnsDomainIs`	yes	yes	yes	yes	yes	yes	yes

Related rules

dnsDomainIs pattern without a leading dot matches look-alike domains PAC-X003
Wildcard characters in dnsDomainIs or localHostOrDomainIs PAC-C004