Subnet Questions on exam

shoegum

Hey Everyone,

i'm looking to take the network+ exam in the coming week, i have done many practice test and feel i know the stuff pretty good to pass. Only thing i usually get stuck on is questions about subnetting. When we get a subnet question on the exam do we actually sit there and figure out all the sub nets and cidr which takes time. if so is there a quick way to figure this out and answer the questions?

here are some of the questions about subnet from practice test im talking about

A company has been given a Class C address to be utilized for all devices. The company has
several subnets and the largest subnet has 15 hosts. Which of the following represents the
MINIMUM CIDR notation of this subnet mask?
A. /26
B. /27
C. /28
D. /29

Which of the following is the minimum subnet mask to allow 172.16.1.5 and 172.16.4.3 to be on
the same subnet?
A. /19
B. /21
C. /22
D. /24

Which of the following IP address/subnet mask combinations represent a broadcast address?
(Select TWO).
A. 200.200.100.0/28
B. 200.200.100.32/27
C. 200.200.100.63/27
D. 200.200.100.79/27
E. 200.200.100.95/27
F. 200.200.100.254/30

srabiee

You have to calculate it out as quickly as possible. You should be able to answer each question in roughly 30 seconds.

This video should help you if you're having problems subnetting without a calculator:

https://www.youtube.com/watch?v=rs39FWDhzDs