networks 1 and 100 are reserved for future delegation.
network 10 is delegated for private networks, such as your
lab.
if you use networks 1 and 100, you are hijacking these
numbers.
that said, as long as your lab is never going to connect
to the Internet, you may want to consider using the following
prefixes:
4.0.0.0/8
38.0.0.0/8
127.0.0.0/8
192.0.0.0/8