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CCNA Reference and Commands Cheat Sheet (DRAFT) by

Full CCNA Reference and Commands Cheat Sheet

This is a draft cheat sheet. It is a work in progress and is not finished yet.

1. Welcome

Welcome text

2. How to Set Up a Lab


3. Host to Host Commun­ica­tions


4. The Cisco IOS Operating System


5. OSI Layer 4 - The Transport Layer


6. OSI Layer 3 - The Network Layer


7. IP Address Classes

Class A addresses
assigned to networks with a very large number of hosts
Class A - /8
Reserved Class A Addresses is reserved and signifies 'this network' to 0.255.2­55.255 are not valid host addresses is the loopback address for the local computer to 127.25­5.2­55.255 are not valid host addresses
Class B addresses
assigned to medium­-sized to large-­sized networks
Class B - 191.25­5.0.0 /16
Class C addresses
used for small networks
Class C - 233.25­5.255.0 /24
Class D addresses
reserved for IP multicast addres­ses**
Class D - 239.25­5.2­55.255
Class E addresses
'experimental and reserved for future use'**
Class E - 255.25­5.2­55.255
Reserved Class E Addresses
255.25­5.2­55.255 is the broadcast address for 'this network'
Private Addresses
assigned to hosts but not routable on the public internet
Class A - 10.255.25­5.255
Class B{{nl}] - 172.31.25­5.255
Class C
192.16­8.0.0 - 192.16­8.2­55.255

8. Subnetting

CIDR - Classless Inter-­Domain Routing
Removes the fixed /8, /16 and /24 address classes and allows them to be split or 'subne­tted' into smaller networks
For example:
Number of available subnets
Example for Class C: network uses /28 subnet
We've borrowed 4 bits from the default Class C /24 subnet
24=16 available subnets
Example for Class B: network uses /28 subnet
We've borrowed 12 bits from the default Class B /16 subnet
212=4096 available subnets
Number of available hosts
Substract 2 for network and broadcast addresses
Example for Class C: network uses /28 subnet
We have 4 bits left for hosts
24-2=14 available hosts per subnet
Example for Class B: network uses /20 subnet
We have 12 bits left for hosts
212-2=4094 available hosts per subnet
VLSM - Variable Length Subnet Masks
Allows using subnets of different sizes in the same network

9. OSI Layer 2 - The Data-Link Layer

**Operates on MAC address and ARP tables

10. OSI Layer 1 - The Physical Layer


11. Cisco Device Functions


12. The Life of a Packet


13. The Cisco Troubl­esh­ooting Method­ology


14. Cisco Router and Switch Basics


15. Cisco Device Management


16. Routing Fundam­entals


17. Dynamic Routing Protocols


18. Connec­tivity Troubl­esh­ooting


19. IGP - Interior Gateway Protocol Fundam­entals


20. OSPF - Open Shortest Path First


21. VLANs - VIrtual Local Area Networks


22. Inter-VLAN Routing


23. DHCP - Dynamic Host Config­uration Protocol


24. HSRP - Hot Standby Router Protocol

R1(con­fig­-if)# standby 1 ip
Add Virtual IP Address
R1# show standby
Show HSRP config­uration
R1(con­fig­-if)# standby 1 priority 110
Set Priority
R1(con­fig­-if)# standby 1 preempt
Set Preemption
If no priority and no preemption is set, the router with the highest interface IP will be used as default

25. STP - Spanning Tree Protocol

Layer 2 Ethernet path selection is controlled by the switch's MAC address table

26. EtherC­hannel


27. Switch Security


28. ACLs - Access Control Lists


29. NAT - Network Address Transl­ation

NAT was implem­ented as a temporary workaround to mitigate the lack of IPv4 addresses

30. IPv6

IPv6 uses a 128bit address, compared to IPv4's 32 bit address

31. WAN - Wide Area Networks


32. The Security Threat Landscape


33. Cisco Device Security


34. Network Device Management


35. QoS - Quality of Service


36. Cloud Computing


37. Wireless Networking Fundam­entals


38. Network Automation and Progra­mma­bility