Cisco CCNA Study Library
200-301
17 free articles on the concepts the 200-301 exam tests, grouped by exam domain. Each one backs real questions in our practice exam.
Network Access
- 802.1Q Trunking on Cisco: Tags, Native VLAN, and Allowed Lists Inside the 4-byte 802.1Q tag, the trunk configuration commands, and the add/remove/except/none keywords that quietly black-hole production VLANs.
- CDP vs LLDP: Timers, Defaults, and What Each Neighbor Table Reveals CDP is Cisco-proprietary and on by default at 60/180 seconds. LLDP is IEEE 802.1AB, off by default at 30/120. Commands, output reading, and security.
- Cisco AP Modes and CAPWAP: Local, FlexConnect, Monitor, Sniffer, Bridge CAPWAP control on UDP 5246 and data on UDP 5247, plus every Cisco access point mode and the deployment scenario each one exists to solve.
- DTP Modes: Which Combinations Actually Form a Trunk Cisco's Dynamic Trunking Protocol decides trunk or access. The full mode matrix, why auto plus auto fails, and where switchport nonegotiate is legal.
- EtherChannel: LACP, PAgP, and On Modes Explained Which channel-group mode pairings actually bundle, how LACP and PAgP differ, where to apply trunk and IP settings, and why one flow never exceeds one link.
- Inter-VLAN Routing: Router-on-a-Stick vs Layer 3 Switch SVIs Router-on-a-stick uses dot1Q subinterfaces on one trunk. A Layer 3 switch uses SVIs plus ip routing. Configuration, failure modes, and design trade-offs.
- Native VLAN Mismatch: Symptoms, Security Risk, and the Fix What happens when trunk ends disagree on the native VLAN: the PVID inconsistency syslog, the CDP warning, the double-tagging attack, and how to clear it.
- PortFast, BPDU Guard, Root Guard, and Loop Guard What PortFast really does, why BPDU guard err-disables a port, why BPDU filter is dangerous, and where root guard and loop guard belong.
- Rapid PVST+: Port Roles, Port States, and Fast Convergence How Rapid PVST+ implements 802.1w per VLAN: the four port roles, the three port states, edge and point-to-point link types, and proposal/agreement.
- Reading show interfaces trunk: Allowed vs Active vs Forwarding The three VLAN lists in show interfaces trunk mean different things. Learn what removes a VLAN from each one and how to diagnose a trunk from the output.
- STP Root Bridge Election: Bridge ID, Priority, and Tiebreakers How the bridge ID, extended system ID, and 4096 priority increments decide the root bridge, plus the root-port tiebreaker chain and default STP path costs.
- VLANs on Cisco Switches: Creating, Assigning, and Verifying Create VLANs, assign access ports, and read show vlan brief on Catalyst switches, including vlan.dat persistence and why deleted VLANs strand their ports.
- Voice VLAN: How a Cisco Phone and a PC Share One Switch Port The switchport voice vlan command, what the phone tags, what the PC sends untagged, and why the feature fails silently without CDP or LLDP-MED.
- VTP Explained: Server, Client, Transparent, and the Revision-Number Outage How VTP synchronizes VLAN databases across Cisco switches, why a client can overwrite a server, and the reset procedure that prevents a campus-wide outage.
- Why an EtherChannel Will Not Bundle Suspended versus stand-alone members, the parameters IOS compares before aggregating, the %EC-5 log messages that name the culprit, and summary flags.
- WLC Ports and Interfaces: Management, Virtual, Dynamic, and Service A wireless LAN controller's physical ports versus its logical interfaces, what each one is for, and the subnet mistakes that break out-of-band management.
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