# Can two networks be part of the same third octet subnet?

Can two networks be part of the same third octet subnet? If both networks are connected to their own respective links, then could their addresses all be a part of the third octet subnet?

Say a network has a subnet mask of 10.47.80.0/24. Since the network prefix takes up 24 bits, we know that we have 8 bits worth of addresses that can be assigned to end systems connected to the subnet 10.47.80.0/24. Also say that I want to assign 128 [2^7 bits] of the addresses to one network and 128 to another. So basically, I want network #1 (which has 128 possible addresses) to be connected to its own link and network #2 (which has the other possible 128 addresses) to be connected to another link. (Both links, of course, would have a link between them).

Would it be possible to spread out all of the addresses of 10.47.80.0/24 over two networks separated by two links?

• `254.47.80.0/24` is an invalid network. Commented Jan 16, 2018 at 4:20
• How is that an invalid network? Commented Jan 16, 2018 at 4:22
• The `240.0.0.0/4` block of addresses is reserved. See the IANA IPv4 Special-Purpose Address Registry, which points you to RFC 1112. Commented Jan 16, 2018 at 4:27

If you are assigned a network, let's pick a valid `10.11.12.0/24` network (not an invalid network, like you have in your question), you can subnet that network into two networks: `10.11.12.0/25` and `10.11.12.128/25`. You then assign those two networks, but you do not assign any other networks from your assigned block anywhere else. You cannot assign overlapping networks without a hassle (VRFs, NAT, etc.), and you really need to know what you are doing and have a good reason for doing it.