# Functions
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".
IsValidIP checks whether ip is valid IP address.
IsValidIPv4 checks whether ip is valid IPv4 address.
IsValidIPv6 checks whether ip is valid IPv6 address.
IsValidPort checks whether p is valid port number.