IETF working group. , a standard for choosing addresses for networked items, was published in March 2005 by the IETF Zeroconf working group. The group included individuals from Apple, Sun, and Microsoft. LLMNR was submitted for official adoption in the IETF DNSEXT working group, however, failed to gain consensus and thus was published as informational in January 2007. Following the failure of LLMNR to become an Internet standard and given that mDNS/DNS-SD is used much more widely than LLMNR, Apple was asked by the IETF to submit the mDNS/DNS-SD specs for publication as Informational RFC as well. In February 2013 mDNS and DNS-SD were published as Standards Track Proposals and . Security issues Because mDNS operates under a different trust model than unicast DNS—trusting the entire network rather than a designated DNS server, it is vulnerable to spoofing attacks by any system within the same broadcast domain. Like SNMP and many other network management protocols, it can also be used by attackers to quickly gain detailed knowledge of the network and its machines. Because of this, applications should still authenticate and encrypt traffic to remote hosts (e.g. via RSA, SSH, etc.) after discovering and resolving them through DNS-SD/mDNS. LLMNR suffers from similar vulnerabilities. Major implementations Apple Bonjour Bonjour from Apple, uses mDNS and DNS Service Discovery. Apple changed its preferred zeroconf technology from SLP to mDNS and DNS-SD between Mac OS X 10.1 and 10.2, though SLP continues to be supported by Mac OS X. Apple's mDNSResponder has interfaces for C and Java and is available on BSD, Apple Mac OS X, Linux, other POSIX based operating systems and MS Windows. The Windows downloads are available from Apple's website. Avahi Avahi is a Zeroconf implementation for Linux and BSDs. It implements IPv4LL, mDNS and DNS-SD. It is part of most Linux distributions, and is installed by default on some. If run in conjunction with nss-mdns, it also offers host name resolution. Avahi also implements binary compatibility libraries that emulate Bonjour and the historical mDNS implementation Howl, so software made to use those implementations can also utilize Avahi through the emulation interfaces. MS Windows CE 5.0 Microsoft Windows CE 5.0 includes Microsoft's own implementation of LLMNR. Systemd Systemd implements both mDNS and LLMNR in systemd-resolved. Link-local IPv4 addresses Where no DHCP server is available to assign a host an IP address, the host can select its own link-local address. Using a