Usually I do not worry about subnet of an IP address on the public Internet, but after I began using Amazon EC2 firewall, it got me thinking.
EC2 firewall configuration requires an IP to be written in CIDR form, if I want to whitelist my home IP (say it is reachable as 1.2.3.4 from public Internet), EC2 firewall config page correctly guesses my home IP 1.2.3.4, and suggestes that CIDR subnet is /24.
Is /24 the magic number of CIDR subnet of any public Internet IP address?