(2^16)-1, or 0-65,535 (the -1 is because port 0 is reserved and unavailable). (edited because o_O Tync reminded me that we can’t use port 0, and Steve Folly reminded me that you asked for the highest port, not the number of ports) But you’re probably going about this the wrong way. There are people who … Read more
It depends on the subnet of the IP address in question. In general, the first and last addresses in a subnet are used as the network identifier and broadcast address, respectively. All other addresses in the subnet can be assigned to hosts on that subnet. For example, IP addresses of networks with subnet masks of … Read more
I found a hiddem gem the other day from Microsoft that is designed for testing ports: Portqry.exe “Portqry.exe is a command-line utility that you can use to help troubleshoot TCP/IP connectivity issues. Portqry.exe runs on Windows 2000-based computers, on Windows XP-based computers, and on Windows Server 2003-based computers. The utility reports the port status of … Read more
IP subnets exist to allow routers to choose appropriate destinations for packets. You can use IP subnets to break up larger networks for logical reasons (firewalling, etc), or physical need (smaller broadcast domains, etc). Simply put, though, IP routers use your IP subnets to make routing decisions. Understand how those decisions work, and you can … Read more