Subnetting is one of those skills that seems intimidating until it clicks, and then it feels obvious. This post builds from first principles — binary representation, masks, and block sizes — through variable-length subnet masking (VLSM) and summarization. IP Address Structure An IPv4 address is 32 bits divided into two …

OSPF link-state advertisements are the currency of the protocol. Understanding which LSA type carries what information — and who generates it — is essential for troubleshooting convergence issues. Quick Reference Type Name Originated By Scope 1 Router LSA Every router Single area 2 Network LSA DR on broadcast segment …