1) Network numbers are defined by a 16-bit number: 2^16 = 65,536. The
network number 0 is reserved to mean unknown, and network number 65,535
is reserved for future use. This means a total of 65,534 networks are
possible.
2) AppleTalk Phase 1 supported 2^8 nodes minus the reserved nodes, ID 0 and
ID 255, which resulted in a total 254 nodes possible. AppleTalk Phase 2
nodes on the physical network are identified by their virtual network
number and their 8-bit node ID. The node IDs of 0, 254, and 255 are
reserved in AppleTalk Phase 2.
Because it is possible to have 65,534 networks with 253 nodes in each
network, it is possible to have a maximum of 16,580,102 nodes (65,534 *
253 = 16,580,102). Note: Network numbers 65,280 through 65,534 are used
only when a router is not present.
3) Actually, the maximum number of physical zones per network is 255. This is
an architectural limitation of AppleTalk Phase 2. The AppleTalk Internet
Router supports a maximum of 255 names on a single zone list. The reason
for 255 is because the zone list may apply to a single physical network.
Also, an AppleTalk Phase 2 internet (1 or more physical networks connected
together via routers) is capable of supporting more than 256 zones. But
the AppleTalk Internet Routers supports a maximum of 256 zones on an
internet.
4) There can be a maximum of 1,024 entries in the routing table for the
AppleTalk Internet Router. Each entry can refer to an individual
network number or a range of network numbers. This limitation is not
AppleTalk Phase 2-specific.