With the command:
/summon Zombie ~ ~1 ~ {Attributes:[{Name:generic.maxHealth,Base:500}]}
survives the Zombie as long as a Zombie summoned with
/summon Zombie ~ ~1 ~ {Attributes:[{Name:generic.maxHealth,Base:50}]} .
With the command:
/summon Zombie ~ ~1 ~ {Attributes:[{Name:generic.maxHealth,Base:500}]}
survives the Zombie as long as a Zombie summoned with
/summon Zombie ~ ~1 ~ {Attributes:[{Name:generic.maxHealth,Base:50}]} .
Enviroment is supposed to be information about your computer
you need to set Health too