Subnetting 122.22.0.0 /22 query

Hi all. I have been given the address: 122.22.0.0 /22 which in binary is 01111010.00010110.00000000.00000000 (bold is 10 bits left for hosts)

and its subnet mask is 255.255.252.0 in binary is 11111111.11111111.11111100.00000000

I am trying to calculate new subnet address when 8 bits left for host (this is a network prefix of /24)

This is what I did:

122.22.0.0 converted to binary with network prefix of /24 is:

01111010.00010110.00000000.00000000 (bold shows 8 bits left for host)

and in decimal new subnet address from my understanding is 122.22.0.0 /24

but correct answer is 122.22.2.0 /24

Why does the 3rd octet is 2 and not 0?

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Comments

10Linefigure

If you have a /24 then your entire last octet is open to hosts. Having your /22 allows for 255.255.252.0 so you have 3.254 as your block size, this allows you to break your Vlans and manage IP's much easier then a /8 , /16, /24 because they leave all the rest as host bits and give you less to work with.

bobfromfpl

If the network prefix is really 01111010.00010110.00000000 (122.22.0) then sounds like the answer is wrong and your initial guess was correct.

Magic Johnson

bobfromfpl wrote: »

If the network prefix is really 01111010.00010110.00000000 (122.22.0) then sounds like the answer is wrong and your initial guess was correct.

I was thinking that, maybe no subnet zero configured or something but then that would be 122.22.1 instead of 2.

bobfromfpl

Yeah, I guess that's a valid assumption but he didn't mention IOS, just subnetting.

Magic Johnson

bobfromfpl wrote: »

Yeah, I guess that's a valid assumption but he didn't mention IOS, just subnetting.

Lol sorry I'm still in Pearson test mode of looking out for gotchas!

vasyvasy

You should be able to use 4 x /24 subnets, like this:

122.22.0.0/24
122.22.1.0/24
122.22.2.0/24
122.22.3.0/24

So your answer is correct, but their answer is also correct

black_lion

vasyvasy wrote: »

You should be able to use 4 x /24 subnets, like this:

122.22.0.0/24
122.22.1.0/24
122.22.2.0/24
122.22.3.0/24

So your answer is correct, but their answer is also correct

Why are they both the same? Im a bit confused

bobfromfpl

black_lion wrote: »

Why are they both the same? Im a bit confused

The subnets are different, they just use the same subnet mask.

Minary

We aren't seeing the question properly. The OP has misquoted it a bit.