In the lab you stated that you can attach 256 resources for a /24 subnet. Does this mean that Azure does not count the network ID or broadcast ID or reserve any other IPs within the subnet?
In Azure, whenever you create a subnet, 5 IP Addresses are reserved. So, a /24 will only give you 251 usable IP addresses instead of 256. This is different from traditional networking where only the network and broadcast addresses are reserved.
What are these 5 addresses used for? See below:
x.x.x.0: Network address
x.x.x.1: Reserved by Azure for the default gateway (this is basically the Azure implicit router interface that you don’t see)
x.x.x.2, x.x.x.3: Reserved by Azure to map the Azure DNS IPs to the VNET space
x.x.x.255: Network broadcast address