boost::urls::ipv6_address::is_loopback Return true if the address is a loopback address Synopsis Declared in header <boost/url/ipv6_address.hpp> bool is_loopback() const noexcept; Description The unicast address 0:0:0:0:0:0:0:1 is called the loopback address. It may be used by a node to send an IPv6 packet to itself. 2.5.3. The Loopback Address (rfc4291)