Hi guys, I am stuck on this. I simple cannot find out where 14 comes from in this problem.
The question is:
What is the maximum number of hosts in a /19 subnet?
And the answer is 8190.
But the way the answer is found is 2^14 - 2. I simple do not understand where the 14 is coming from?!
It cannot be the binary 0s:
11111111 11111111 11100000 00000000
There are only 13 of them!
Does anyone know?
You might want to check their online Book Errata assuming they have one because if you put in 14 you’d get a ridiculous answer, their answer was correct but the calculation seriously flawed due to the wrong number.
Most of Networking theory is simple; it is just that there is an ‘awful lot’ to memorise. 
I have the Cisco Press CCNA 1 to 4 Books and even those have a few faults marked in their online book errata site - obviously I passed/completed the whole CCNA course two years back. Although I do remember it took me a while to fully absorb CIDR and VLSM (Variable-Length Subnet Masks).
Thanks a lot man, that was baffling me, so I know the answer in the book is incorrect then. I was originally thinking the only number I possibly could get was 13. The book is the official Comptia Network+ book!
It has been a couple of years since I’ve done CIDR in my head (so I am rusted) but the answer looks correct.
CIDR mask: 225.225.224.0 (11111111 11111111 11100000 00000000)
19 Mask Bits
8192 (Max) Subnets
8190 (Addresses)
/19 (32 Class C Networks), (19 Network ID bits), (13 No. Of Host ID bits), [8,192 Total number of Host addresses per segment = (2 [1]#[/B] of Host ID bits)], [8,190 Number of usable Host addresses per segment= (2 [2]#[/B] of Host ID bits)-2]
Remember with CIDR you also aggregate but the calculation was; 2^13 = 8192 and 2^13-2 = 8190.
I don’t know where you got 14 from.