ICND1 Cheat Sheet 2026

The 30 highest-yield ICND1 facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which protocol is commonly used to dynamically assign IP addresses in a LAN? → DHCP
2. Which debug command would help identify why OSPF neighbor adjacencies are not forming? → debug ip ospf adj
3. Which protocol is used by MPLS to distribute label information between routers? → LDP (Label Distribution Protocol)
4. Which command configures a default route on a Cisco router and forwards traffic to next-hop 203.0.113.1? → ip route 0.0.0.0 0.0.0.0 203.0.113.1
5. Which professional attribute is most valued in ospf configuration within the ICND1 field? → Accountability and commitment to standards
6. What does the IPv6 prefix FF02::1 represent? → All nodes on the local link
7. Which of the following best describes a classless routing protocol? → It includes subnet mask information in routing updates
8. Which SNMP version introduced strong authentication and encryption for secure network management? → SNMPv3
9. What is the fundamental principle behind infrastructure maintenance in the ICND1 domain? → Balancing performance, reliability, and efficiency
10. What is the total number of bits in an IPv6 address? → 128
11. What does Cisco's Per-VLAN Spanning Tree Plus (PVST+) do differently from standard 802.1D STP? → It runs a separate STP instance for each VLAN, allowing per-VLAN Root Bridge placement
12. What is the value of continuing education in ipv4 and ipv6 for ICND1 professionals? → It keeps professionals current with evolving standards and practices
13. On a Cisco switch, which file stores VLAN configuration by default when VTP is in server or client mode? → vlan.dat
14. On a Cisco switch, which inter-VLAN routing method uses a single physical trunk link to a router with subinterfaces? → Router-on-a-stick
15. Which statement correctly describes the difference between symmetric and asymmetric encryption? → Symmetric uses one key for both encryption and decryption; asymmetric uses a key pair
16. A host has IP 172.16.45.200/20. What is the network address of this subnet? → 172.16.40.0
17. How does the ICND1 body of knowledge relate to daily professional practice? → It provides the foundational framework that guides decision-making and standard practices
18. Which feature prevents rogue DHCP servers from assigning IP addresses on a network? → DHCP snooping
19. What is the most important professional competency for ICND1 certification in troubleshooting? → Deep knowledge combined with practical application skills
20. Which SNMP operation allows the NMS to modify a value on a managed device? → Set
21. What is the purpose of the 'switchport nonegotiate' command on a trunk port? → Disables DTP so the port does not send DTP frames
22. Which layer of the OSI model is responsible for logical addressing and routing? → Layer 3 – Network
23. Which Cisco IOS command enables IPv6 routing on a router? → ipv6 unicast-routing
24. Two switches are connected with an EtherChannel bundle. Which load-balancing method uses both source and destination MAC addresses? → src-dst-mac
25. Which encapsulation type must be configured on both ends of a serial link when connecting Cisco routers to non-Cisco devices? → PPP
26. What is the PRIMARY benefit of using data-driven decision making in Interconnecting Cisco Networking Devices Part 1 management? → It provides objective evidence to support decisions, reduce bias, and track outcomes
27. Which command sets the OSPF reference bandwidth to 1000 Mbps to correctly calculate costs for Gigabit interfaces? → auto-cost reference-bandwidth 1000
28. An IPv6 address is written as 2001:0DB8:0000:0000:0000:0000:0000:0001. What is its compressed form? → 2001:DB8::1
29. What is the MOST effective way for new ICND1 professionals to build competency in their field? → Combining formal education, mentored practice, and ongoing professional development
30. What is the primary function of the Routing Information Protocol (RIP)? → To determine the best route based on hop count