# What is a subnet mask for beginners?

## What is a subnet mask for beginners?

A subnet mask doesn’t represent any device or network on the Internet. It’s just a way of indicating which portion of an IP address should be used to determine the network ID. (You can spot a subnet mask right away because the first octet is always 255, and 255 is not a valid first octet for any class of IP address.)

## What is a subnet for dummies?

A subnet is a network that falls within a Class A, B, or C network. Subnets are created by using one or more of the Class A, B, or C host bits to extend the network ID. Thus, instead of the standard 8-, 16-, or 24-bit network ID, subnets can have network IDs of any length.

How do you create a subnet?

Procedure

1. Click the Network tab.
2. In the Subnets tab, click Create.
3. In the Create Subnet dialog box, specify subnet details, such as the name, subnet IP address or subnet mask, range of IP addresses, gateway address, and broadcast domain.
4. Click Create.

How do I set up a subnet?

### What is a subnet mask and what does it do?

A subnet mask is used to divide an IP address into two parts. One part identifies the host (computer), the other part identifies the network to which it belongs. To better understand how IP addresses and subnet masks work, look at an IP address and see how it’s organized.

### How do you split a VPC into a subnet?

For example, if you create a VPC with CIDR block 10.0. 0.0/24 , it supports 256 IP addresses. You can break this CIDR block into two subnets, each supporting 128 IP addresses. One subnet uses CIDR block 10.0.

How do you calculate subnet mask?

A more mathematical way to express the the subnet mask calculation is: current value = value on the left (previous value) + power of 2 of this column. It should take about 1 minute to do this when the exam starts. It will be extremely useful all through the exam to double check any IP and subnet.

Steps Click the Network tab. In the Subnets tab, click Create. In the Create Subnet dialog box, specify subnet details, such as the name, subnet IP address or subnet mask, range of IP addresses, gateway address, and broadcast domain. You can specify the IP addresses as a range, as comma-separated multiple addresses, or as a mix of both.

What is the default subnet mask?

The subnet Masks indicate which portion of an IP address denotes the network and which portion denotes the host. The subnet mask for class C IP addresses is 255.255.255.0 and is the default subnet mask for many computers and network routers.

## How many IP addresses in a subnet?

Every subnet (connected through a gateway) needs at least 3 addresses: network, broadcast, gateway. subnet with 10 hosts: 4 bit host part (28 bit mask length) => 16 IP addresses – 3 – 10 – 1 (for the switch) = 2 free addresses will rest.