Showing 10 of 16 Blog Posts
Dynamic Trunking Protocol (DTP) explained: the 5 modes, which pairs form a trunk, how switch spoofing abuses it, and how to turn it off without an outage.
What is DHCP? The DORA process, why it's UDP 67 and 68 (and when it's 67 both ways), lease timers, relay, and Cisco IOS server config with...
VTP (VLAN Trunking Protocol) explained: modes, versions, the revision number that wipes VLANs, DTP, exam coverage, and when to use transparent, off or v3.
Router on a stick routes between VLANs on one Cisco interface. Full IOS config, the native VLAN line everyone forgets, verification, and the five failures that break...
LACP bundles physical links so spanning tree sees one port, not four. Config, active vs passive, and the STP cost trap when a member link fails.
What is NAT? Network Address Translation explained with working Cisco configs for static NAT, dynamic NAT and PAT, plus verify and troubleshooting commands.
BPDU guard shuts a port the moment a rogue switch sends a BPDU. What it blocks, the config commands, and how to recover an err-disabled port.
RSTP converges in under a second where legacy STP takes 30 to 50. Port roles, the three port states, the proposal and agreement handshake, Cisco config, and...
Multiple spanning tree protocol maps many VLANs to a few STP instances. MST regions, IST and CIST, the full Cisco config, and when to pick it over...
Spanning tree protocol stops switching loops by blocking redundant links. Root bridge election, BPDUs, port states, RSTP vs MSTP, and a three-switch lab you can build tonight.