Internet protocol requirements

An internet protocol must meet the requirements for a protocol as well as the additional requirements listed below.

In the table below, X denotes an internet protocol class, a denotes a value of type X, and b denotes a value of type X.

Table 15. InternetProtocol requirements

expression	return type	assertion/note pre/post-conditions
`X::resolver`	`ip::basic_resolver<X>`	The type of a resolver for the protocol.
`X::v4()`	`X`	Returns an object representing the IP version 4 protocol.
`X::v6()`	`X`	Returns an object representing the IP version 6 protocol.
`a == b`	convertible to `bool`	Returns whether two protocol objects are equal.
`a != b`	convertible to `bool`	Returns `!(a == b)`.