subnetting question

I have a question about subnetting a class c ip address. At work I am required to take training classes and todays lecture was on subnetting. I have learned to subnet in the past but I don't get to use it in my job so I was a little rusty. Anyways to make a long story short and the conclusion of our class the instructor asked us to subnet this address: 192.56.10.0

He wanted us to create 4 netowrks with 50 hosts each. I immediately thought that this was impossible. If I need 4 networks I need to use 3 bits for subnetting, that would give me a possible 6 networks. But with only 5 bits left for the host I could only use 30 hosts.

The instructor said to ignore the rfc's rules. I didn't know that was allowed but I did it anyway. We are only doing this stuff on paper. Anyway what I did and this is what the instructor wanted was to use 255.255.255.192 as my subnet mask. I know normally I could only create two networks: 192.56.10.64 & 192.56.10.128. My instrctor said you can also use
192.56.10.0 with the range going to 63 (62 if you don't count the broadcast address) and 192.26.10.192 with the range going to 255. I got the right answer in class but I am skeptical if that is legal. I know when I learned it it was not but the instructor said that has been changed. Can anyone straighten me out on this. Someone out there must know or be able to direct me somewhere I can find out. Please Help!!!

 

legal? Humm... subnet cco on Cisco has all the rules of subnetting. I tried to link it but once I log in, the link won't work for you... have you googled it yet?