SUBNETTING QUESTIONS 4 | Find the Subnet Mask from IP Address

SUBNETTING QUESTION 4

With an IP address set starting with 150, you currently have six offices that you are treating as subnets. Plans are in place to open 10 more offices before the end of the year. What subnet mask should you use to satisfy the needed number of subnets and maximize the number of hosts available at each site?

Solution

A/Q, Our requirement is 6+10 = 16 Subnets with minimum 150 host

Hence we need minimum 150 IP Address on each network. It means we cannot borrow a single bit from the last octet. Because, if you borrow a single bit you will get less then 150 IP Address.

So, we have to borrow 4 bits from the third octed. (2⁴=16 Subnets) and here you will get (2¹² – 2 = 4094 IP Address) on each network.

(11111111.11111111.11110000.00000000)

(2⁷ + 2⁶ + 2⁵ + 2⁴ + 2³ + 2² + 2¹ + 2⁰) . (2⁷ + 2⁶ + 2⁵ + 2⁴ + 2³ + 2² + 2¹ + 2⁰) . (2⁷ + 2⁶ + 2⁵ + 2⁴) . (0)

So the subnet mask is 255.255.240.0 with maximum number of host.

Subnetting Tutorial

IPv4 SUBNETTING Tutorial | Calculate the Subnet Mask, IP Address from CIDR