I may be trying to teach Granny to suck eggs here but you cannot flout the rules.
Subnet masks must always be a series of 1's then 0's. You cannot mix and match. The mask is used to separate the host and network portions ie the last non-zero octet must always be one of 192, 224, 240, 248 or 252 (254 is allowed in Class A in the second or third octet or Class B in the third octet but not in either case the fourth octet). 128 is also not allowed to be the next octet from the standard netmask for each class in subnetting.
All the following netmasks allow no hosts Class A netmasks 255.255.255.254 or 255.128.0.0.0 Class B netmasks 255.255.255.254 or 255.255.128.0 Class C netmasks 255.255.255.254 or 255.255.255.128
The idea of classes A, B and C is something like a decade out of date, the original idea was that the subnet mask could be worked out by looking at the first octet of the IP address. -- Mark Evans St. Peter's CofE High School Phone: +44 1392 204764 X109 Fax: +44 1392 204763