Multiple Subnets sharing a switch (no VLAN)

[taraz0007]

Is it possible to have multiple subnets sharing a single switch (without VLANs or routers)?

If so, what would happen?

Would the broadcast traffic be restricted to a single subnet, or would both subnets recieve the broadcast traffic (e.g., one broadcast domain or two)?

Would the subnets be completely isolated from each other?

Would the subnets be able to communicate?

Would the switch work, even though some of the devices would have a different network address?

[markanderson]

Yes, it is possible to have multiple subnets in the same virtual local area network (VLAN). You would just assign multiple subnets under the same VLAN interface but it is not a common practice at all.  The cleanest way is to have one subnet per vlan to keep you broadcast domains separate.

[Joseph W. Doherty]

Yup, very simple to have multiple networks on the same L2 media, concurrently.  Things get a bit more involved, though, when dealing with the question of intercommunication between those networks, which was asked in the original posting and in @DaveVA's posting.  For such a question, just having multiple addresses on a SVI, alone, may not other hosts, on those network, to intercommunicate.  (Of course if the SVI is on a L3 switch, with IP routing enabled, and all the hosts are using the SVI's IP, on their network as their gateway, yup, that should work.)