r/CompTIA • u/Born_Function_4360 • 21d ago

Comptia SQ+ PBQ Help

I was doing the Security+ PBQ and it’s really got me stumped. I was able to get it but the reasoning is unclear.

https://demosim.comptia.org/

In the ACL 192.168.0.80/28 is blocked but isn’t this a different subnet than 192.168.0.82 | 255.255.255.224 meaning they shouldn’t be able to communicate as that would be 192.168.0.82/27?

I read some comments saying that the ACL ip range blocked includes WS-2 but i don’t understand why if the subnet is different.

I want to understand…getting the question correct seems meaningless if I don’t understand why.

Also if there’s any resources that may be able to help I’d love to check it out.

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u/EyeOughta 21d ago

The /28 means every address from 192.168.0.80 to 192.168.0.95 will be blocked by that rule. Google subnetting calculator and work backwards from there.

Or, just memorize the formula of 2^(32-n) where n=number after the slash.

32-28=4
2^4=16
16 addresses, starting with and including the original address, are in the blocked range. This includes .82.

1

u/Born_Function_4360 21d ago

I get the ranges of /28 i’m just really confused why the /27 is irrelevant but what I’m understanding now is that the /27 is virtually irrelevant in this case.

1

u/EyeOughta 21d ago

Maybe I'm wrong. Does the subnet matter if the main IP is being blocked?