Cisco CCNA Cheat Sheet 2026

The 30 highest-yield Cisco CCNA facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. A client roams from AP1 to AP2, both managed by the same WLC. Which type of roaming occurs? → Intra-controller roaming where the WLC updates client mapping internally
2. What does the 'I' stand for in the CRUD acronym used with REST APIs? → CRUD does not contain an 'I'
3. Which DNS record type maps a fully qualified domain name (FQDN) to an IPv4 address? → A record
4. A router running OSPFv2 shows 'Dead interval mismatch' in debug output when attempting to form a neighbor adjacency. Which action resolves this? → Configure matching Dead intervals on both routers' connecting interfaces
5. Which command on a Cisco switch assigns a physical interface to EtherChannel group 1 using LACP active mode? → channel-group 1 mode active
6. A network technician is reviewing IP configurations on a local area network. Which of the following IP addresses is a valid RFC 1918 private address? → 10.1.1.25
7. What is the purpose of NAT overload (PAT) in a network? → To allow multiple internal hosts to share a single public IP address using port numbers
8. In which scenario does the OSI Session layer play a critical role? → Managing dialog control between two applications in a video conference
9. A time-based ACL uses which command to reference a defined time range? → time-range
10. Which feature protects against IP address spoofing by verifying that incoming packets match an entry in the DHCP snooping binding table? → IP Source Guard
11. What differentiates an SSID from a BSSID in WLAN terminology? → SSID is the human-readable network name; BSSID is the MAC address of the AP radio
12. A router interface is configured with 'ipv6 address 2001:DB8:A:1::/64 eui-64'. What does the eui-64 keyword cause the router to do? → Derive the interface ID from the interface's MAC address using EUI-64
13. Which IOS command defines a NAT pool named MYPOOL with addresses 198.51.100.1 through 198.51.100.10 and a /28 mask? → ip nat pool MYPOOL 198.51.100.1 198.51.100.10 netmask 255.255.255.240
14. Which command is used to verify which VLANs are forwarding on a specific trunk interface? → show interfaces trunk
15. Which STP port state forwards data frames but does NOT learn MAC addresses? → Listening
16. What happens when the MAC address table of a switch becomes full? → The switch floods all new unknown frames like a hub
17. What is the default violation mode for Cisco switch port security? → Shutdown
18. Which IPv6 address type is equivalent to the IPv4 private address space? → Unique local
19. What happens when you delete vlan.dat from the switch's flash memory? → All normal-range VLAN configurations are erased and reset to defaults
20. What does the 'inside global' address represent in NAT terminology? → The public IP assigned to an internal host as seen from the outside
21. Which show command displays the OSPF router ID, process ID, area information, and SPF statistics? → show ip ospf
22. In a REST API, what does the endpoint '/api/v1/devices/{id}' with a DELETE method accomplish? → Removes the device with the specified ID
23. What happens when a packet matches a permit statement in an ACL? → The packet is forwarded and no further ACL entries are checked
24. What are the ones that are used with NAT? → All of the above
25. Which STP feature automatically sets a port to the Forwarding state when connected to an end device, bypassing the Listening and Learning states? → PortFast
26. Which OSPF state indicates that two routers have fully synchronized their Link State Databases? → Full
27. Which OSI layer converts data between formats such as encryption, compression, and character encoding? → Presentation (Layer 6)
28. Which wireless security protocol replaced TKIP with CCMP/AES as its mandatory encryption method? → WPA2
29. What is the minimum RSA key size recommended when generating SSH keys on a Cisco IOS device for SSHv2? → 2048 bits
30. Which of the following protocols is a Distance Vector Protocol? → RIP