Cisco IOS File Management & Maintenance: Backup, Archive, Rollback
Working reference for Cisco IOS file management. The running vs startup config distinction (RAM vs NVRAM) and copy run start as the most-forgotten command, backing up to TFTP / FTP / SCP including credential setup, the file system layout (flash, nvram, system, tftp:, scp:, usbflash0), running the router itself as a TFTP server, the archive feature for automatic config snapshots with path / write-memory / time-period, configure replace for non-disruptive rollback (it computes the diff vs copy which is additive only), archive log config for audit logging with hidekeys redaction, verify /md5 for IOS image integrity, and the pitfalls (TFTP file-must-exist trap, plaintext FTP creds, insufficient flash before image upgrade).