Question

if I want to set a network in a company, this network consist of a PCs, laptops and a printer;

given that the number of needed host (PCs and laptops) is 73.

how many subnets are possible?

and how many subnets are required?

what is the number of usable IP addresses that are needed?

please help with a detailed answer so i can learn how to calculate other similar questions

Answer 1

For 73 Host,

Possible addresses- 128

We can consider 255.255.255.128 net mask that are available for 126 hosts.

The total number of IP addresses in a subnet is a power of two. So that's: 1, 2, 4, 8, 16, ... etc.

The first IP address in a subnet is a multiple (0, 1, 2, 3 ...) of the number of IP addresses in the subnet.

For example you started with IP address-192.168.1.24 for subnet- 255.255.255.128

IP Address:	192.168.1.24
Network Address:	192.168.1.0
Usable Host IP Range:	192.168.1.1 - 192.168.1.126
Broadcast Address:	192.168.1.127
Total Number of Hosts:	128
Number of Usable Hosts:	126
Subnet Mask:	255.255.255.128
Wildcard Mask:	0.0.0.127
Binary Subnet Mask:	11111111.11111111.11111111.10000000
IP Class:	C

• All 2 of the Possible /25 Networks for 192.168.1.*

Network Address	Usable Host Range	Broadcast Address:
192.168.1.0	192.168.1.1 - 192.168.1.126	192.168.1.127
192.168.1.128	192.168.1.129 - 192.168.1.254	192.168.1.255

/25 -- 2 Subnets -- 126 Hosts/Subnet

Network #	IP Range	Broadcast
.0	.1-.126	.127
.128	.129-.254	.255

• Size: 128

Netmask: 255.255.255.128 or /25
Starts with multiple of 128;
Note: This is a rather large subnet.

'd' in IP address a.b.c.d;

1st - last	1st - last
0 - 127	128 - 255