Cisco CCNA Study Guide 2026
Everything you need to pass the Cisco CCNA exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 Cisco CCNA Exam Format at a Glance
📚 Cisco CCNA Topics to Study (69)
✍️ Sample Cisco CCNA Questions & Answers
1. An OSPF router is in the 'Exstart' state. What is occurring at this stage?
In the Exstart state, OSPF neighbors determine master/slave roles and agree on the initial Database Description sequence number before exchanging LSAs.
2. Which STP feature automatically sets a port to the Forwarding state when connected to an end device, bypassing the Listening and Learning states?
PortFast allows a port to transition directly to Forwarding, skipping Listening and Learning, and is intended for ports connected to end hosts.
3. Which SNMP version introduced authentication and encryption for secure management communications?
SNMPv3 added user-based security with MD5/SHA authentication and DES/AES encryption, replacing the community-string model.
4. How many ACLs can be applied per interface per direction?
Cisco IOS allows only one ACL per interface per direction (one inbound and one outbound).
5. Which attack does DHCP snooping protect against on a switched network?
DHCP snooping prevents rogue DHCP servers by only forwarding DHCP offers from trusted (uplink) ports, blocking unauthorized IP assignments.
6. Which command disables CDP on a specific Cisco router interface to prevent neighbor information disclosure?
The interface-level command 'no cdp enable' disables CDP on that specific interface without affecting other interfaces.