Can I mix 10Base2 and 10Base5 cabling on a single segment?
It is not “legal”, but the network police will not read you your rights and drag you away. Ideally, you should use a repeater (or bridge, router, etc…) between the different cabling types. However, in reality, it will work fine, as long as none of the other network parameters (lengths, numbers of stations, repeaters, etc) are near the limit of the specification.
