# MS exams 0s and 1s ...

Member Posts: 55 ■■□□□□□□□□
This will be my next exam after 290, my question is on how the answers will asked do they add +2 (as in leaving the address the same as 2^4=16 and not 2^4=16-2)on the subnet side and -2 on the host side.

I think this is kinda complicated to read but the rfc 1812 allow for the 1s and 0s to be counted on the subnet or the network side of the ip address is there a rfc for the router seein the 1s and 0s on the host side of the IP addess.

Thanks Gateway ...

• Member Posts: 232
AndreL wrote: »
This will be my next exam after 290, my question is on how the answers will asked do they add +2 (as in leaving the address the same as 2^4=8 and not 2^4=8-2)on the subnet side and -2 on the host side.

I think this is kinda complicated to read but the rfc 1812 allow for the 1s and 0s to be counted on the subnet or the network side of the ip address is there a rfc for the router seein the 1s and 0s on the host side of the IP addess.

2^4=16

Take a look at:
Blogging my AWS studies here! http://www.itstudynotes.uk/aws-csa
• Member Posts: 4,214 ■■■■■■■■□□
Is there a lot of subnetting in the 291?
Decide what to be and go be it.
• Member Posts: 633 ■■■□□□□□□□
They do allow use of the scientific calculator in Windows during the exam, or so I've been told. I'll let you know for sure next week.
[size=-2]Started WGU - BS IT:NDM on 1/1/13, finished 12/31/14
Working on: Waiting on the mailman to bring me a diploma
• Go ping yourself... Member Posts: 2,333 ■■■■■■■□□□
AndreL wrote: »
This will be my next exam after 290, my question is on how the answers will asked do they add +2 (as in leaving the address the same as 2^4=16 and not 2^4=16-2)on the subnet side and -2 on the host side.

I think this is kinda complicated to read but the rfc 1812 allow for the 1s and 0s to be counted on the subnet or the network side of the ip address is there a rfc for the router seein the 1s and 0s on the host side of the IP addess.

Thanks Gateway ...

For the sake of the 291 exam, I think it is safe to say that you will always have to subtract 2 for the correct host ranges. So if I have 192.168.40.0/20 then I know my subnets are:

192.168.40.0
192.168.56.0
192.168.72.0
192.168.88.0
etc..

Each subnet has 4094 valid hosts, and those ranges are:

192.168.40.1 - 192.168.55.254
192.168.56.1 - 192.168.71.254
192.168.72.1 - 192.168.87.254
192.168.88.1 - 192.168.103.254
• Member Posts: 4,214 ■■■■■■■■□□
According to CBT Nuggets you subtract 2 for the maximum available hosts, but do not need to for the maximum number of subnets.

I learned subnetting about 2 years ago and was taught to subtract 2 for both. But according to James, you haven't had to subtract 2 from the subnet since 1995.
Decide what to be and go be it.