Free Cisco CCNA practice questions

Sample question 1. A syslog entry shows traffic from 172.20.77.9/20. To build a matching route summary, the engineer needs the subnet ID of that host's /20 subnet. What is it?

1. 172.20.72.0, the nearest multiple of 8 below 77
2. 172.20.77.0, because the subnet matches the host's third octet
3. 172.20.0.0, the start of the 172.20.0.0/16 block that holds the host
4. 172.20.64.0, the start of the 16-wide block that holds 77

Sample question 2. Two switches are joined by a full-duplex link. When the link comes up, the designated port moves to forwarding within about a second rather than waiting 30 seconds. What makes this possible in RSTP?

1. Shorter forward-delay timers, which RSTP sets to 1 second by default
2. A proposal and agreement handshake between the switches on the point-to-point link
3. PortFast being enabled automatically on each full-duplex link
4. CDP confirming that the neighbor is a Cisco switch before forwarding

Sample question 3. A router runs software with a known flaw in its web interface. An attacker group is scanning the internet for that flaw, and a public script can take advantage of it. In this scenario, what is the software flaw itself?

1. The threat, because it could cause harm to the organization
2. The exploit, because a public script already exists for it
3. The vulnerability, a weakness that could be exploited
4. The mitigation, because patching it will remove the risk