Use this tag for questions that relate directly to systemd's version of resolved. Do not use this tag for dnsmasq or regular resolved.
systemd-resolved is a DNS resolver bundled with systemd at installation. It's primary focus (like any DNS resolver) is to provide hostname resolution for a system.
systemd-resolved, in particular, supports technologies such as LLMNR and DNSSEC. It also caches DNS queries as needed in order to increase the speed of future lookups.
To end users, there should be zero practical difference between systemd-resolved and the currently-existing dnsmasq. For administrators, it will slightly change configurations and system setups, but it can be replaced with dnsmasq if needed for legacy purposes.
systemd-resolved reads /etc/resolv.conf, and will optionally provide it. According to FreeDesktop's page on systemd-resolved, there are three operation modes for /etc/resolv.conf management, usually involving symlinks.
systemd-resolved is due to hit Ubuntu in version 17.04.
