can someone pls help me fill this out :(( i dont get it aaa

>>60858788
do your own homework

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8KB, 251x206px

>>60858840
/g/ pls i rly dont get how to do this

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60KB, 600x400px

>>60858788
What is it?

>>60858867
Convert it to binary.
See how many 1s there are at the start of the relevant octet, then change the remaining numbers to 0s and convert it back into a decimal number.

By the way, are you studying for a CCNA, and do you live in England? My work has put me on a course of exactly this that I need to go to Birmingham for, and I wouldn't be surprised if some of the people there also posted on /g/.

>>60858788
I literally just googled "configuring subnet mask"

https://www.lifewire.com/internet-protocol-tutorial-subnets-818378

>>60858788

Visualize it using binary

Let's take a range of

IPs: 192.168.0.0 to 192.168.3.255
Subnet Mask: 255.255.252.0

The subnet mask for 255.255.255.0 would look like this in binary

11111111 11111111 11111111 00000000

For every 1 you turn into a 0 subtracts in a base 2 increment.

Now taking a look at the IP range given above, that's 4 subnets, minus the 0 from the first and the 255 of the last subnet which are reserved for Subnet and Broadcast addresses respectively.

In order to figure out how we get the 255.255.252.0 mask, this is how you'd do it in binary

11111111 11111111 11111111 00000000 : 255.255.255.0, 1 Subnet
11111111 11111111 11111110 00000000 : 255.255.254.0  2 Subnets
11111111 11111111 11111100 00000000 : 255.255.252.0  4 Subnets

Since the pattern is n^2, odd numbers are not possible unless you do VLSM

Once you start understanding

>>60862355

Learning CIRD notation is also handy. Subnets are defined as /X where X is the number of 1's (or 32 minus the number of 0's for IPv4, which works from the direction of least significant numbers).
When you get the hang of it, you can work out netmasks quickly.
e.g. 255.255.0.0 is /16 (32 -8 -8)
255.255.224.0 is /19 (32 - 5 -8); the 5 comes from 256-224=32, which is 2^5 & the 8 comes from 256-0 = 2^8

ymmv. Other people can pick up their methodologies.

>>60862928
CIRD? I though it was CIDR, but yes, it's also helpful especially when dealing with Variable Subnet Length Masks