server 2 & 3
========
$ sudo apt install mariadb-server
Reading package lists... Done
Building dependency tree
Reading state information... Done
mariadb-server is already the newest version (10.1.14+maria-1~xenial).
0 upgraded, 0 newly installed, 0 to remove and 4 not upgraded.
server 1
========
$ sudo apt install mariadb-server
Reading package lists... Done
Building dependency tree
Reading state information... Done
mariadb-server is already the newest version (10.1.15+maria-1~xenial).
0 upgraded, 0 newly installed, 0 to remove and 4 not upgraded.
What is actually happening here?