# Functions
Source: https://golang.org/src/net/dnsclient.go IsDomainName checks if a string is a presentation-format domain name (currently restricted to hostname-compatible "preferred name" LDH labels and SRV-like "underscore labels"; see golang.org/issue/12421).nolint:gocyclo.
JoinHostPort combines host and port into a network address of the form "host:port" or, if host contains a colon or a percent sign, "[host]:port".
SplitHostPort splits a network address of the form "host:port", "host%zone:port", "[host]:port" or "[host%zone]:port" into host or host%zone and port.