Assessment Brief

Need some help with sub-netting questions using VLSM.
Use subnet 0 in all answers.
(a)  Given the network 140.50.0.0/16:
(i) Create a
subnet mask for 400 subnets with the maximum possible number of hosts in each
subnet
(ii) find the
address of the 250th subnet
(iii) VLSM
the network address calculated in part (ii) above for as many sub-networks as
possible, with no more than 14 usable hosts in each sub-network. Show the
subnet mask used. 
Show and
explain all your working along with your answers.
(b) Create a
suitable route summarised (aggregated) address and subnet mask for the
following networks:
192.168.74.0/16
192.168.75.0/16
192.168.76.0/16
192.168.77.0/16
192.168.78/0/16
Show and
explain all your working along with your answer.
(c) Describe
in your own words how a switch knows about the hosts connected to it in a wired
Ethernet LAN. In your answer you should consider the type of addressing used
and how this relates to the physical connection of the host to the switch. By
reference to hosts PC1 and PC2 list the events used by the switch to learn the
LAN configuration.