So, if you have a sane ipv4 network, where everything is dhcp, and nothing apart from a few key things are statically assigned, then yeah _technically_ you can

So, if you have a sane ipv4 network, where everything is dhcp, and nothing apart from a few key things are statically assigned, then yeah _technically_ you can have 16million addresses all at once. But, subnets need to be located next to each other physically, otherwise performance suffers. subnets have affinity. but once you have subnets, you then start loosing packing efficiency. for example, in the batshit world of K8s, you give each node its own /24 to dish out. Not only cant that limit the number of containers you can host, it also is really inefficient. (eating 256k addresses) More over, it also means that you need to reuse addresses. in a large cluster of say 1000 nodes, each hosting 40 containers, starting/stopping anything up to 30 containers a second isn't unreasonable. Its not inconceivable that you'll end up trying to connect to a stale address (either because its not propagated yet, or your brand of service discovery isn't that fast). This can cause hilarious transitory errors. but if you could assign an IP per container, and have enough space to not re-use that address for at least a few hours then that goes away. so instead of getting weird fuzzing errors(or misc 404/401), you get a connection timed out.