CCNA 3 Revision Notes
CCNA 3 Revision Notes: Enterprise Networking, Security, and Automation
1. Routing Concepts
Static Routing
- Manually created using:
ip route [destination_network] [subnet_mask] [next_hop | exit_interface]
- Default Route:
ip route 0.0.0.0 0.0.0.0 [next-hop | exit-int]
Dynamic Routing Protocols
- OSPF: Link-state, uses cost metric, builds full network topology.
- EIGRP: Cisco proprietary, advanced distance-vector, uses bandwidth & delay as metrics.
2. LAN Redundancy
STP (Spanning Tree Protocol)
- Prevents Layer 2 loops.
- Roles: Root, Designated, Blocked Ports.
- Elects a Root Bridge based on priority + MAC.
RSTP
- Faster convergence.
- Uses handshake instead of timers.
EtherChannel
- Aggregates links for redundancy and speed.
- LACP (open) and PAgP (Cisco).
3. Link Aggregation
- Bundles multiple links into one logical interface.
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CCNA 3 Revision Notes
- LACP: IEEE standard.
4. Wireless LANs (WLANs)
Components
- Access Points (APs), Wireless LAN Controllers (WLCs), Clients.
Modes
- Infrastructure (with AP), Ad hoc (peer-to-peer).
Standards
802.11b - 2.4 GHz - 11 Mbps
802.11g - 2.4 GHz - 54 Mbps
802.11n - 2.4/5 GHz - 300 Mbps
802.11ac - 5 GHz - 1+ Gbps
Security
- Prefer WPA2/WPA3 over WEP.
- Use AES over TKIP.
5. WAN Technologies
Connection Types
- Leased Line, MPLS, Broadband, VPN.
Protocols
- PPP: Supports authentication.
- HDLC: Cisco default.
- GRE: Tunnels for encapsulation.
QoS
- Prioritizes traffic.
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CCNA 3 Revision Notes
- Methods: Classification, Marking, Scheduling.
6. VPN Concepts
Types
- Site-to-Site, Remote Access.
IPSec
- AH (auth only), ESP (encryption + auth).
- Uses AES, SHA.
7. Infrastructure Security
Port Security
- Limits MACs per port.
- Violation: Protect, Restrict, Shutdown.
DHCP Snooping
- Prevents rogue DHCP servers.
DAI (Dynamic ARP Inspection)
- Blocks ARP spoofing.
ACLs
- Standard: Source IP only.
- Extended: Protocol, source/destination IPs, port numbers.
8. Device Management & Monitoring
Syslog
- Logs system events. Levels 0 (emergency) to 7 (debug).
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CCNA 3 Revision Notes
NTP
- Synchronizes time.
SNMP
- Monitors device status.
SSH vs Telnet
- SSH = Secure.
9. Network Automation & Programmability
SDN
- Separates control and data planes.
- Centralized control via controller.
REST APIs
- Use HTTP verbs (GET, POST, etc.) to interact with devices.
Formats
- JSON, YAML.
Tools
- Ansible, Netmiko, RESTCONF, Python scripting.
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