Cisco IOS Basic Configuration: Interfaces, Sub-interfaces, DHCP, CDP, and Banners
Working reference for baseline Cisco IOS configuration. The hostname / domain / no ip domain-lookup trio (the latter saves 20 seconds per typo), Layer 3 interfaces with description / ip address / no shutdown, sub-interfaces for router-on-a-stick with encapsulation dot1Q including the native keyword, loopback interfaces for management and router-id, the Null0 bit-bucket, clock rate / bandwidth on serial, full DHCP server config (excluded-address, pool, default-router, dns-server, lease) and ip helper-address for relay, CDP enable/disable per-interface, MOTD/login/exec banners, clock + NTP, disabling the HTTP server, and the baseline template every new router should start from.