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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
1.0.0.0 - 126.0.0.0 /8
Reserved Class A Addresses
0.0.0.0/8 is reserved and signifies 'this network'
0.0.0.1 to 0.255.2­55.255 are not valid host addresses
 
127.0.0.0/8 is the loopback address for the local computer
127.0.0.1 to 127.25­5.2­55.255 are not valid host addresses
Class B addresses
assigned to medium­-sized to large-­sized networks
Class B
128.0.0.0 - 191.25­5.0.0 /16
Class C addresses
used for small networks
Class C
192.0.0.0 - 233.25­5.255.0 /24
Class D addresses
reserved for IP multicast addres­ses**
Class D
224.0.0.0 - 239.25­5.2­55.255
Class E addresses
'experimental and reserved for future use'**
Class E
240.0.0.0 - 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
10.0.0.0/8
10.0.0.0 - 10.255.25­5.255
Class B{{nl}]172.16.0.0/16
172.16.0.0 - 172.31.25­5.255
Class C
192.168.0.0/16
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: 175.10.10.0/20
Number of available subnets
2subnet­-bits
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
2host-bits-2
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 10.10.10.1
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

R1(con­fig)#text
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