Network Troubleshooting

A workstation connected to a FastEthernet port on a local switch experiences extremely slow speeds and dropped packets. When examining the switch interface statistics, a network administrator observes a high count of late collisions and frame check sequence (FCS) errors on the port. Which of the following configuration issues is the most likely cause of these symptoms?

A desktop computer connected to an office Ethernet port is unable to communicate with external web servers or internal resources. A technician reviews the network interface status and observes an assigned IPv4 address of $169.254.108.99$ with a subnet mask of $255.255.0.0$. Which of the following conditions is the most likely cause of this issue?

A network administrator needs to determine the exact distance along a 90-meter copper Ethernet cable run to locate an open circuit break hidden inside a wall. Which tool should the administrator use to measure the distance to the fault?

A network engineer is troubleshooting high CRC frame error rates and severe throughput degradation on a newly installed 90-meter Category 6A UTP cable drop connecting a server to a 10GBASE-T switch port. A basic wiremap continuity test shows all eight conductors properly terminated in pin-to-pin alignment, and a standard Time-Domain Reflectometer (TDR) reports no opens, shorts, or impedance discontinuities along the cable run. However, the link fails to sustain 10Gbps auto-negotiation without dropping packets. Which diagnostic hardware tool or measurement parameter is specifically required to pinpoint the root cause of this performance failure?

A network technician needs to inspect a local workstation to view all currently active TCP connections, listening ports, and protocol statistics. Which command-line utility should the technician execute?

A network administrator is troubleshooting an issue where hosts on a local subnet cannot reach a remote database server across a routed network boundary. Place the following diagnostic and remediation steps in the correct sequential order according to standard network troubleshooting methodology.

A network technician receives a ticket stating that IP phones on VLAN 30 attached to Switch-B cannot communicate with the VoIP call manager connected to Switch-A. However, workstations on VLAN 10 attached to the same switches are communicating across the interconnecting 802.1Q trunk link without any issues.

An inspection of Switch-B's trunk port configuration reveals the following entry:
`switchport trunk allowed vlan 10,20`

Which of the following identifies the root cause of the connectivity failure for VLAN 30 traffic?

A network administrator is investigating a name resolution failure on a corporate workstation. Standard DNS queries for small host records complete successfully, but queries returning large responses (such as DNSSEC queries) time out, as shown in the following CLI output:

$ dig +dnssec internal.example.com
;; Truncated, retrying in TCP mode.
;; communications error to 10.0.0.1#53: connection timed out
;; communications error to 10.0.0.1#53: connection timed out
;; no servers could be reached

Which of the following network misconfigurations is the most likely root cause of this failure?

During a data center infrastructure audit, network engineers discover that a 70-meter Category 6A UTP cable run connecting an end-of-row switch to a server cabinet continuously negotiates down to 1 Gbps instead of establishing a stable 10GBASE-T link. A basic wire mapper confirms all eight conductors maintain correct end-to-end continuity without open or short circuits. Further testing with a cable certifier identifies severe Near-End Crosstalk (NEXT) originating at the patch panel termination point. Inspection reveals that 5 cm (2 inches) of conductor pairs were untwisted prior to punching them down into the Insulation Displacement Connector (IDC) blocks. What physical mechanism caused the NEXT failure, and how should it be remediated?

A network administrator is troubleshooting connectivity issues for a workstation assigned the static IPv4 address $192.168.50.140/26$. The workstation can communicate with local hosts on its subnet ($192.168.50.128/26$), but cannot connect to a secure web portal hosted externally at $203.0.113.50:443$.

During diagnostic collection, the administrator notes the following settings:
- Workstation IPv4 Address: $192.168.50.140$
- Subnet Mask: $255.255.255.192$
- Configured Default Gateway: $192.168.50.1$
- Router Interface Inbound ACL Rule:
`permit tcp 192.168.50.128 0.0.0.63 host 203.0.113.50 eq 80`

Which TWO configuration issues are preventing the workstation from establishing a connection to the external web portal?

A network administrator is diagnosing several Layer 2 switching and trunking issues across a enterprise campus network. Match each observed switch diagnostic symptom or log message on the left to its corresponding underlying root cause on the right.

Users on a corporate subnet ($10.20.4.0/24$) intermittently experience network connectivity loss accompanied by IP address conflict warnings. A network technician discovers that a new network printer was manually configured with the static IP address $10.20.4.15$. The local DHCP server scope is configured for $10.20.4.1/24$ with a distribution pool ranging from $10.20.4.10$ through $10.20.4.254$. Which of the following actions on the DHCP server is the best resolution to permanently prevent this conflict?

A network technician is assigned to troubleshoot a user workstation that cannot access local network resources. Place the following diagnostic and resolution steps in the correct order, starting from the initial physical check to the final connectivity verification.

A network administrator is investigating a report that a newly provisioned workstation cannot access an internal line-of-business portal at `portal.dev.company.local`. The administrator executes two command-line diagnostic queries from the workstation:

Query 1:

> nslookup portal.dev.company.local
Server: 192.168.1.1
Address: 192.168.1.1#53

** server can't find portal.dev.company.local: NXDOMAIN

Query 2:

> nslookup portal.dev.company.local 10.10.10.5
Server: 10.10.10.5
Address: 10.10.10.5#53

Name: portal.dev.company.local
Address: 10.10.10.45

Which of the following is the most likely root cause of this name resolution failure?

Match each physical network cabling fault or symptom on the left with its most likely physical root cause on the right.

A network technician is equipping a field kit with diagnostic tools for physical and protocol-level troubleshooting. Match each diagnostic tool to the scenario where it provides the required functionality.

Match each Layer 2 switching diagnostic symptom or log output on the left with its primary underlying root cause on the right.

A network administrator receives multiple alerts indicating severe latency and packet drops across a enterprise wireless network deployment following a software update on the central wireless LAN controller (WLC). Arrange the technician's troubleshooting actions in the correct sequence according to the CompTIA troubleshooting methodology, from first step to last step.

A system administrator is troubleshooting network reachability on a newly provisioned server configured with IP address $172.16.14.78$ and subnet mask $255.255.255.192$ ($/26$). The server can communicate with local host devices on its broadcast domain, but fails to send packets to remote subnets. The default gateway interface on the switch router is assigned $172.16.14.65/26$. Upon reviewing the server's network configuration, the administrator notes that the default gateway entry is configured as $172.16.14.62$. Which of the following accurately identifies the root cause of this routing issue?

A network administrator is troubleshooting poor Wi-Fi performance and frequent disconnections in an enterprise office space. A site survey reveals severe adjacent-channel interference on the 2.4 GHz band due to access points (APs) operating on channels 3 and 8. Furthermore, users working at the outer perimeter of the building experience signal degradation, with RSSI readings dropping below $-85\text{ dBm}$ on the 5 GHz band. Which of the following actions should the network administrator take to resolve these wireless connectivity issues? (Select TWO.)