CCNA Network Exam Prep 2026 practice questions and answers. Tap an option to test yourself — you'll see the correct answer and a plain-English explanation for every question. Free, no login.
Q21What is the wildcard mask for a subnet with a prefix length of /30?
✓ Correct answer: A. 0.0.0.3
Answer: 0.0.0.3 A prefix length of /30 leaves 2 bits for host addresses. In a wildcard mask, each bit of the subnet mask is inverted. For a /30 subnet mask (255.255.255.252), the wildcard mask is 0.0.0.3.
Q22Which command is used to enable EIGRP routing on a router?
✓ Correct answer: B. router eigrp 1
Answer: router eigrp 1. The command "router eigrp 1" is used to enable EIGRP routing on a router. It specifies the routing protocol (EIGRP) and the autonomous system number (1). The "network" command associates an IP address with the EIGRP process, but does not enable it. The "router-id" command is used to specify the router ID in other routing protocols. The "hostname" command sets a hostname for the device.
Q23Which command configures a static IPv6 address on an interface?
✓ Correct answer: D. ipv6 address 2020::10/64
Answer: ipv6 address 2020::10/64 The command "ipv6 address 2020::10/64" is used to configure a static IPv6 address on an interface. It includes the IPv6 address and prefix length. The command "ip address 2020::10/64" is incorrect because it uses the "ip" keyword, which is for IPv4 addresses. The command "ipv6 address ::/0" is invalid because it sets an inappropriate prefix length of 0. The command "ip address 192.168.1.1/24" is entirely an IPv4 configuration.
Q24Which routing protocol uses bandwidth as its metric to determine the best path?
✓ Correct answer: C. OSPF
Answer: OSPF OSPF (Open Shortest Path First) uses bandwidth as its metric to determine the best path. Specifically, it considers the cumulative bandwidth of the route links. RIP uses hop count as its metric. EIGRP and IGRP use a combination of metrics including bandwidth, delay, load, and reliability known as K values.
Q25Which two lines of output from the 'show ip interface brief' command indicate that an interface is administratively down? (Choose two.)
✓ Correct answer: B. FastEthernet0/0 unassigned YES unset administratively down down
The 'show ip interface brief' command provides a quick overview of the device's interfaces, their IP addresses, and their operational status. An interface that is administratively down is indicated by the 'administratively down' status in the 'Status' column and the 'down' state in the 'Protocol' column.
Q26An administrator runs the "show ip eigrp neighbors" command and receives the output shown below. In this output, a neighbor with a Q-value of 0 indicates that the neighbor is in the Established state, while any non-zero Q-value indicates the neighbor is not yet fully established. Based on the table provided, how many neighbors are not in the Established state? Address Interface Hold Uptime SRTT RTO Q Seq 10.1.1.2 Gi0/1 13 00:01:23 150 9 4626 10.1.1.3 Gi0/1 12 00:01:25 150 6 4627 10.1.1.4 Gi0/1 11 00:01:24 150 0 4625 10.1.1.5 Gi0/1 14 00:01:29 150 3 4628
✓ Correct answer: D. 3
Answer: 3. A Q-value of 0 indicates the neighbor is in the Established state. Neighbors with non-zero Q-values (10.1.1.2, 10.1.1.3, and 10.1.1.5) are not in the Established state.
Q27Which security concept determines the identity of a device trying to connect to a network?
✓ Correct answer: D. Device Authentication
Answer: Device Authentication Device Authentication is the process of verifying the identity of a device attempting to connect to a network. Common methods include certificates and digital signatures. Device Authorization concerns what a device is allowed to access. Device Accounting is about tracking what a device did on the network. Device Automation is not related to security concepts for controlling user access.
Q28Router R1 has an interface Fa0/1 connected to a network with a trusted NTP server and interface Fa0/2 connected to untrusted hosts. All ports are in VLAN 20. Which two commands should be included when configuring the router for NTP Authentication? (Choose two.)
✓ Correct answer: A. ntp authentication-key 1 md5 <password>
To use NTP Authentication, it has to be configured for the VLAN. The first command to run is "ntp authentication-key 1 md5 <password>" which specifies the key ID, authentication type, and password. The second command is "ntp authenticate" to enable authentication on the router. The "show ntp associations" command displays NTP associations. The "ntp access-group" command is used to control NTP access based on ACLs. The "switchport trunk encapsulation dot1q" command is used to configure trunk encapsulation on a switch interface.
Q29Which four practices enhance network security? (Choose four.)
✓ Correct answer: A. Use VPNs for remote access.
There are multiple practices that can fortify network security. Implementing strong firewall rules helps in preventing unauthorized access. Regularly updating network devices ensures protection against vulnerabilities. Using VPNs for remote access adds another layer of security. Network segmentation divides the network into sections to limit the impact of security breaches. Disabling unused ports and services reduces the attack surface. Consistent monitoring and logging of network activity aid in early detection of malicious behavior.
Q30Which type of software is specifically designed to identify and exploit vulnerabilities in computer systems?
✓ Correct answer: D. Exploit
Answer: Exploit An exploit is a piece of software or code that is used to take advantage of a vulnerability in a computer system. It can be in the form of scripts, malware, or other malicious tools designed to perform unauthorized actions. A vulnerability is a weakness in a system that can be exploited. A threat is any potential malicious actor who might use an exploit against a vulnerability. A mitigation technique refers to any strategy or method used to prevent or reduce the damage of a threat or exploitation.
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Theory