Alright two more which got me puzzled.
-What is the valid host range from 172.31.1.134 /28?
Answer = 172.31.1.129 - 172.31.1.142
**I worked it out to be 172.31.1.128-172.31.1.144. I see my mistake as from number to number should be 14 hosts but remember this question as it will affect my reasoning for the next one pertaining to it being a Class B address yet the subnet 255.255.240.0 is only causing me to make adjustments to the last octet**
In this question, you don't really need to worry about classes. A /28 gives you a block of 16 addresses and that's all you really need to be concerned with here.
-What is the broadcast of 10.190.208.0 255.255.240.0?
Answer = 10.190.223.255
**I answered incorrectly of 10.190.208.254. What the hell? This is the exact same subnet (255.255.240.0) as the first question and the only difference is that this is a Class A address. Since the Class B address above had me only changing the last octet (in the d class range) so i assumed it was the same for this question as its the same subnet. Now it seems like if i have a Class A address i should always change the 3rd octet while Class B address's have me change the 4th octets. Makes no sense to me that its skipping an octet. I would assume by logic that if i have a Class A address such as this on (10.190.208.0) then i have free range to change numbers after the first octet (the 190.208.0) and if i had a Class B address then i could change the third octet over. In these two questions it turned out that a Class A can only change the third octet and on and Class B changes only 4th octet.
Please tell me how stupid i am and where i am going wrong? Am i overthinking it?
Again, forget about classes on this one, that's only going to add extra complexity you don't need to worry about here. A /20 gives you an increment of 16 in the third octet, so the range of this subnet will be 10.190.208.0 through 10.190.223.255 (or one address less than the beginning of the next subnet, 10.190.224.0 (208 + 16 = 224)). The broadcast address for this network is the last valid address, or 10.190.223.255.
Until you get all this back committed to memory, it helps to have a cheat sheet handy. Go here
and grab the IPv4 Subnetting Cheat Sheet (I kept a lot of these handy when I was working on the CCNA). You can also go here
to check your work.