From the TCP/IP model, IP addressing, CIDR, and NAT to network configuration, routing, DNS, firewalls, and troubleshooting — the concepts every developer needs and the Linux commands that put them to work.
Cidr
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Linux Networking Fundamentals -
Subnetting Explained: Why Subnet Masks Aren't Just 255s and 0s A from-intuition walk through subnetting, and a direct answer to the question every beginner eventually asks: would you ever use a subnet mask octet that isn't 255 or 0? Yes — constantly — and here is exactly when and why.