Network Troubleshooting

A network engineer is troubleshooting an issue where hosts on VLAN 10 ($10.45.8.0/24$) can ping their default gateway interface ($10.45.8.1$), but cannot establish TCP connections to an application cluster on VLAN 50 ($10.45.50.0/24$). Diagnostic commands reveal that the intermediate Core-Router shows its OSPF adjacency with the Distribution Switch stuck in the EXSTART/EXCHANGE state across their interconnect subnet ($10.45.200.0/30$). Additionally, large packet pings with the Don't Fragment (DF) bit set fail without receiving any diagnostic response. Which TWO of the following root causes or misconfigurations are most likely responsible for this behavior?

A network engineer is troubleshooting an issue where client computers can establish a basic TCP handshake with a remote application server across an IPsec VPN tunnel, but bulk data transfers fail or time out. The engineer suspects that packets exceeding the tunnel's Maximum Transmission Unit (MTU) are being dropped because path MTU discovery is failing.

Which of the following command-line utility commands should the engineer run on a Windows workstation to test reachability while setting the Don't Fragment flag to identify the maximum unfragmented payload size?

Following a network resegmentation, a workstation on VLAN 30 ($192.168.30.0/24$) is unable to communicate with network resources. The workstation's network adapter is set to acquire an IP address automatically. Running `ipconfig /all` on the workstation yields the following output:

IPv4 Address. . . . . . . . . . . . : 169.254.48.19
Subnet Mask . . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . . :
DHCP Server . . . . . . . . . . . . :

The central DHCP server resides on VLAN 10 ($192.168.10.15$). The network administrator inspects the router's configuration for the subinterface corresponding to VLAN 30 and notes that the interface is operational with IP $192.168.30.1/24$, but no relay commands are present.

Which of the following statements accurately diagnose this issue and identify the necessary corrective action? (Select TWO.)

Employees working in a newly expanded section of an office building report frequent wireless disconnections and degraded network throughput on their laptops connecting via the 2.4 GHz band. A network administrator conducts a site survey and finds that three neighboring access points covering the area are currently configured to use Channels 1, 3, and 5. Which of the following identifies the primary cause of this performance issue and the correct action to resolve it?

A network technician is investigating severe performance degradation across an enterprise network following an after-hours maintenance window. After reviewing syslog messages and analyzing traffic patterns, the technician suspects that an incorrectly configured Link Aggregation Control Protocol (LACP) bundle on a core switch stack is creating a Layer 2 switching loop. To test this theory, the technician temporarily disables one of the aggregated member interfaces, which instantly drops CPU utilization back to baseline levels and restores network throughput. According to the CompTIA troubleshooting methodology, which of the following actions should the technician perform next?

A network technician needs to inspect a host computer's local cache to view the mapping of IP addresses to physical MAC addresses. Which command-line utility should the technician execute?

A network administrator is diagnosing Layer 2 operational issues across several switch ports in an enterprise campus network. Match each observed switch log message or diagnostic symptom on the left to its correct underlying root cause on the right.

A network technician needs to inspect live network traffic and decode packet headers passing through a server's network interface to troubleshoot an application issue. Which of the following tools are packet analyzers designed for this task? (Select TWO.)

A network administrator provisions a new subinterface on a branch router to serve VLAN 50 (`192.168.50.0/24`). Workstations connected to VLAN 50 fail to obtain network configuration parameters and continuously assign themselves addresses in the `169.254.x.x` range. Meanwhile, devices on VLAN 10 connected to the same switch successfully acquire leases from the centralized DHCP server at `10.10.10.50`. The technician inspects the router subinterface configuration:

text
interface GigabitEthernet0/0/1.50
encapsulation dot1Q 50
ip address 192.168.50.1 255.255.255.0

Which of the following configuration changes on the router interface will resolve the connectivity issue for VLAN 50 hosts?

A network technician is troubleshooting a client workstation that failed to obtain an IP address from the DHCP server and auto-configured an APIPA address. Arrange the standard troubleshooting methodology steps in the correct sequential order from first step to last step.

A network technician is troubleshooting a point-to-point wireless bridge spanning 250 meters between two corporate buildings. Signal strength readings indicate a strong Received Signal Strength Indicator (RSSI) of -51 dBm, but the link suffers from high packet corruption, fluctuating bit rates, and intermittent dropouts whenever large cargo trucks cross the intervening parking lot. Which of the following is the most likely cause of this wireless performance issue?

A network technician deploys three wireless access points across an office building to provide coverage on the 2.4 GHz band. Users report frequent packet loss, slow speeds, and dropped connections when moving near areas covered by multiple access points. Upon inspecting the wireless controller, the technician observes that the access points are manually configured to operate on channels 1, 2, and 3, respectively. Which of the following is the most likely cause of the wireless performance degradation?

A network technician has established a theory of probable cause regarding a workstation's loss of network connectivity. According to the CompTIA troubleshooting methodology, which of the following actions should the technician take NEXT?

A network technician is setting up three wireless access points in a small office on the 2.4 GHz band. The technician notices performance issues and interference when using channels 1, 2, and 3. Which channel assignment strategy should the technician use to eliminate channel overlap?

In a high-ceiling logistics warehouse with large metal shelving units, wireless handheld inventory scanners experience severe frame loss (~40%) and dropped connections despite exhibiting a strong Received Signal Strength Indicator (RSSI) reading of $-52\text{ dBm}$. A packet analysis reveals a massive spike in $802.11$ Layer 2 retransmissions and corrupted preamble headers. Spectrum analysis confirms no adjacent or co-channel Wi-Fi networks exist in the area. Which of the following wireless phenomena is the primary root cause of this degraded performance?

A network administrator is troubleshooting severe latency and intermittent connectivity issues for users in an open-office environment. A recent site audit reveals three 802.11n wireless access points (APs) mounted on the same ceiling grid, operating on the 2.4 GHz band and configured on channels 1, 3, and 5. Which of the following identifies the primary cause of the wireless performance degradation, and what is the proper solution?

Match each wireless connectivity issue to its primary cause.

Match each wireless network symptom or issue to its corresponding root cause or scenario description.

A network technician is investigating reports of intermittent dropouts and low data rates for mobile workstations in a newly renovated wing of a medical facility. The access point status indicates normal operational health, but a site measurement near the reinforced concrete walls shows a received signal strength indicator (RSSI) of -84 dBm compared to -52 dBm in the central hallway. Which of the following is the most likely cause of the degraded wireless performance?

Users in an enterprise office report severe latency and high packet loss when connected to the 2.4 GHz Wi-Fi network near a central atrium. A spectral scan reveals several neighboring access points operating on channels 3, 4, and 5 with 40 MHz channel widths. Which TWO of the following actions should the network administrator take to resolve the wireless signal degradation? (Select TWO.)