All practice questions

A network engineer observes that hosts on VLAN 10 connected to Switch-Alpha are unexpectedly able to communicate with hosts on VLAN 20 connected to Switch-Beta across an 802.1Q trunk link without traversing a Layer 3 router. Console logs on Switch-Alpha report a CDP native VLAN mismatch warning indicating GigabitEthernet0/1 is in native VLAN 10, while Switch-Beta reports native VLAN 20 on its connecting port. Which of the following technical explanations accounts for this cross-VLAN communication behavior?

Mobile laptop users in an enterprise environment report dropped VoIP calls and high latency when moving between offices. Wireless diagnostic logs show that client devices remain attached to a distant access point (AP) at $-83\text{ dBm}$ RSSI, despite being positioned directly underneath a nearby AP. An RF audit reveals that both 2.4 GHz and 5 GHz radios on all APs are operating at maximum transmit power ($+23\text{ dBm}$). Which of the following administrator actions will best remediate this sticky client roaming issue? (Select TWO.)

A network administrator is investigating a sudden connectivity disruption in a fulfillment center where mobile handheld scanners are receiving APIPA ($169.254.x.x$) addresses and failing to communicate with the warehouse management system. Place the following troubleshooting steps in the correct sequential order according to the CompTIA troubleshooting methodology, from the initial step to the final step.

A workstation on a local network is configured to obtain an IP address dynamically. Arrange the four messages of the DHCP lease acquisition process (DORA) in the correct chronological sequence from start to finish.

Match each physical layer cabling issue or measurement requirement on the left with the most appropriate diagnostic tool or technique on the right.

A network technician is troubleshooting name resolution issues on a Linux client system. The client can successfully reach internal resources by IP address, but system applications fail to resolve the hostname `app.lab.internal`.

The technician executes a targeted query using `dig` and receives the following output:

$ dig @172.16.0.10 app.lab.internal A

; <<>> DiG 9.16.1-Ubuntu <<>> @172.16.0.10 app.lab.internal A
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41258
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; QUESTION SECTION:
;app.lab.internal. IN A

;; ANSWER SECTION:
app.lab.internal. 3600 IN A 172.16.50.25

Despite the direct query returning a valid record from `172.16.0.10`, standard system tools and web browsers on the workstation still fail to resolve `app.lab.internal`. Which of the following potential root causes could explain this behavior? (Select TWO.)

A network administrator is troubleshooting an issue where a workstation configured with IP address $10.200.48.50$ and subnet mask $255.255.240.0$ (/20) can communicate with other hosts on its local network but cannot access external destinations. Running `traceroute 198.51.100.25` fails immediately on the first hop. Reviewing the workstation's network settings reveals that the default gateway is configured as $10.200.64.1$. Which of the following is the root cause of the connectivity issue?

A systems administrator is configuring a newly deployed Linux server assigned the IPv4 address $172.31.88.45/22$ (subnet mask $255.255.252.0$). The server can successfully ping other local hosts within its local network segment, but fails to reach any external subnets or remote application servers. The administrator inspects the host network interface and routing table using standard command-line tools:

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.31.88.45 netmask 255.255.252.0 broadcast 172.31.91.255

Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 172.31.92.1 0.0.0.0 UG 100 0 0 eth0
172.31.88.0 0.0.0.0 255.255.252.0 U 0 0 0 eth0

Which of the following identifies the root cause of the remote connectivity failure?

Match each physical cabling or connector defect with its primary root cause or characteristic physical symptom.

A network engineering team plans to reconfigure VLAN trunking and update Spanning Tree Protocol priorities across campus core switches during an upcoming maintenance window. The lead engineer is finalizing the formal change control documentation for submission to the Change Advisory Board (CAB). Which of the following components must be included in the documentation to ensure the team can safely undo modifications if an unexpected broadcast storm occurs during implementation?

A network administrator is troubleshooting connectivity between a corporate client workstation ($172.16.40.25/24$) and an off-site secure web server ($192.168.200.10/24$). The client can successfully ping its default gateway ($172.16.40.1$), but connection requests to the web server over HTTPS time out.

The administrator reviews the inbound Access Control List (ACL) applied to the client's router interface:

text
Extended IP access list 101_INBOUND
10 permit tcp 172.16.40.0 0.0.0.255 host 192.168.200.10 eq 80
20 deny ip 172.16.40.0 0.0.0.255 any
30 permit tcp 172.16.40.0 0.0.0.255 host 192.168.200.10 eq 443

Which of the following identifies the root cause of this connection failure?

A technician is troubleshooting a newly installed twisted-pair Ethernet cable run that fails to establish a link. A basic wire mapper indicates that pin 1 on one end is wired to pin 3 on the other end, and pin 2 is wired to pin 6. Which TWO of the following actions or tools should the technician use to resolve and verify this specific cabling issue?

Match each wireless connectivity symptom observed in an enterprise network environment to its underlying RF phenomenon or configuration cause.

A network administrator is troubleshooting an issue where hosts on a newly provisioned user subnet (VLAN 50, $10.50.10.0/24$) are receiving APIPA IPv4 addresses ($169.254.x.x$) instead of valid leases from the central DHCP server located on VLAN 10 ($10.10.10.2$). Place the diagnostic and remediation steps in the correct logical sequence from initial verification to final resolution confirmation.

A network technician is following the standard CompTIA troubleshooting methodology to resolve a remote gateway connectivity failure reported on a client workstation. Place the troubleshooting steps in the correct sequential order from first to last.

A network security administrator is configuring an IPsec Remote Access VPN using IKEv1 Main Mode. Place the four primary operational steps of the IKE handshake process into the correct chronological sequence from start to finish.

A network security engineer configures a stateful firewall to protect an internal database server residing at $10.0.1.50$ that receives connections from an application server at $10.0.2.10$ over TCP port $1433$. An inbound rule permitting traffic from source IP $10.0.2.10$ to destination IP $10.0.1.50$ on TCP port $1433$ is explicitly applied. Although no explicit outbound rule is created to permit return traffic from the database server back to the application server's ephemeral ports, communication functions normally without packet drops. Which of the following best explains why the return traffic is successfully permitted through the firewall?

A network administrator is designing a wireless infrastructure upgrade to implement WPA3-Enterprise across corporate headquarters. The design must ensure individual user accountability, centralized authentication, and protection against management frame spoofing attacks. Which of the following technical specifications and security mechanisms are required for this deployment? (Select TWO.)

A network technician is troubleshooting a newly installed 2.4 GHz Wi-Fi deployment in a open-plan office. Users report frequent packet drops and inconsistent throughput despite showing strong signal indicators on their devices. A wireless spectrum analyzer reveals heavy adjacent-channel interference between three neighboring access points currently configured to operate on channels 1, 3, and 5 with 20 MHz channel widths. Which of the following actions should the technician take to resolve the wireless interference and optimize performance?

A network technician deployed an emergency configuration change to an edge router during an unscheduled service outage to restore connectivity quickly. Now that network services are fully restored and stable, which TWO of the following post-emergency procedures are required to maintain proper configuration and change management compliance?