Category: Addressing & Segmentation

Learn how subnetting works, how to make an IP static without clashes, and how NAT type is separate from local addressing. Use a subnet example, DHCP scope, gateway, and DNS.

Learn how IPv4 class labels relate to CIDR, private and public ranges, and NAT status. Compare your device IP, gateway, WAN IP, public IP, and port behavior to find your NAT type.

Subnet masking explained with a worked IPv4 example: calculate your local range, then compare the gateway, public IP, upstream device, and application tests to spot NAT type.

NAT type tester results make sense once you compare local IPs, gateway status, and public IPs to spot public subnet, private subnet, shared carrier-grade NAT, double NAT, and inbound access issues.

Learn what an IP subnet is, how prefixes divide address space, and how to calculate network, broadcast, usable hosts, and increments using modern CIDR and legacy Class B terms.

Learn which IPv4 ranges are private, public, and Class D multicast, and how an IP address manager tracks subnets, leases, reservations, DNS links, and conflicts.

Learn how subnetting works with CIDR: calculate IPv4 network, broadcast, usable-host, and next-subnet values, then recognize Class D multicast addresses and group traffic.

/25 subnet mask explained in dotted decimal and binary, with step-by-step network, broadcast, and usable-host calculations, plus how it fits with Class B IP addresses and CIDR today.