Basically, An active device is any type of circuit component with the ability to electrically control electron flow (electricity controlling electricity). Thus, transistor is an active device. 

Note that active device doesn't mean it just produces energy.

All active devices control the flow of electrons through them. Some active devices allow a voltage to control this current while other active devices allow another current to do the job. 

Devices utilizing a static voltage as the controlling signal are called voltage-controlled devices. 

Devices working on the principle of one current controlling another current are known as current-controlled devices.

BJT is current controlled, while FET is voltage controlled active device.

Why a Transistor is considered to be an active device?
My hostname is localhost, reported by hostname command, and terminal prompt root@localhost:~#.

How can i change it to mismis.com with mismis alias? and what is the proper configuration.

I confused after reading some articles on web.

My /etc/hosts:

127.0.0.1       localhost
127.0.1.1       srv345.myweb.com      srv345
178.162.231.61  janstone.mismis.com    janstone
# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

