Network Troubleshooting

A network technician is troubleshooting an issue where workstations in a remote branch office cannot resolve hostnames within the internal domain `internal.corp.com`, although external internet domains resolve normally. The technician runs diagnostic commands from a affected workstation with the following results:

> nslookup internal.corp.com
Server: 192.168.1.1
Address: 192.168.1.1#53

** server can't find internal.corp.com: SERVFAIL

> dig @10.10.20.5 internal.corp.com
;; QUESTION SECTION:
;internal.corp.com. IN A

;; ANSWER SECTION:
internal.corp.com. 3600 IN A 10.10.20.50

Based on the output, which TWO of the following are the most likely root causes of this name resolution failure? (Select TWO.)

A network technician is investigating why users on subnet $10.20.4.0/24$ cannot access a secure internal web portal at $10.20.10.15$ over HTTPS. The technician runs a traceroute command from a client workstation ($10.20.4.50$), which yields the following output:

Traceroute to 10.20.10.15 over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms 10.20.4.1
2 2 ms 1 ms 2 ms 10.20.1.2
3 * * * Request timed out.

An inspection of the router at $10.20.1.2$ reveals the following inbound Access Control List (ACL) applied on interface GigabitEthernet0/1:

access-list 105 permit tcp 10.20.4.0 0.0.0.255 host 10.20.10.15 eq 80
access-list 105 permit icmp 10.20.4.0 0.0.0.255 host 10.20.10.15

Based on these diagnostic outputs, which of the following is the root cause of the connection failure?

A network technician plugs a newly deployed workstation into switch port GigabitEthernet0/12. The host successfully obtains an IP address in the default management network (192.168.1.0/24) and can reach local hosts in that same network, but it is unable to access any resources on the Finance subnet (192.168.30.0/24). An inspection reveals that the switch port is still using its factory default configuration. Which of the following is the most likely cause of this connectivity issue?

A network technician is troubleshooting a workstation that cannot access external web services. Arrange the command-line network utilities in the correct logical sequence of execution to systematically isolate the issue from the local host configuration to external path reachability and name resolution.

A network technician is troubleshooting a connectivity issue where hosts on VLAN 20 ($192.168.20.0/24$) are unable to access an enterprise application server at $10.100.50.25$. Place the following diagnostic and remediation steps in the correct order according to standard CompTIA network troubleshooting methodology, from first step to last step.

A network administrator is conducting a post-implementation review of a enterprise wireless deployment across various campus zones. Match each observed wireless signal anomaly to its underlying radio frequency (RF) or configuration cause.

A network technician is inspecting a newly terminated Cat 6 Ethernet patch cable that is failing to transmit data. To confirm that each of the eight individual conductors is connected to its corresponding pin on both ends without any open circuits or shorts, which diagnostic tool should the technician use?

A network administrator is troubleshooting network reachability for a newly installed server in an enterprise datacenter. The host is assigned the IPv4 address $172.16.50.130$ with a subnet mask of $255.255.255.192$ ($/26$). The administrator discovers that while the host can ping its local loopback address, it cannot establish SSH connections to a remote server at $172.16.50.200/26$ or reach external networks.

The host IP configuration is verified as follows:
- IPv4 Address: $172.16.50.130$
- Subnet Mask: $255.255.255.192$
- Default Gateway: $172.16.50.126$

The router interface servicing this VLAN is configured as follows:
text
interface GigabitEthernet0/0.50
encapsulation dot1Q 50
ip address 172.16.50.129 255.255.255.192
ip access-group VLAN50_IN in
!
ip access-list extended VLAN50_IN
permit tcp 172.16.50.128 0.0.0.63 any eq 22
permit icmp 172.16.50.128 0.0.0.63 any

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

Match each physical network cabling fault or diagnostic condition on the left with its underlying physical cause on the right.

A workstation on a corporate network is unable to connect to local network resources or access the internet. A technician executes `ipconfig /all` on the workstation and observes an IPv4 address of $169.254.45.12$ with a subnet mask of $255.255.0.0$. Which of the following is the most likely cause of this connectivity issue?

Following a recent core switch update, enterprise workstations connected to VLAN 30 ($10.30.0.0/24$) fail to communicate outside their local subnet. Preliminary reports indicate workstations are assigning themselves addresses in the range $169.254.0.0/16$. Place the following diagnostic and remediation steps in the correct chronological sequence to isolate and resolve this DHCP assignment failure according to standard network troubleshooting methodology.

A network analyst suspects that an improper MTU size configuration on a newly deployed site-to-site IPsec VPN gateway is causing large HTTPS file transfers to fail. The analyst performs a ping sweep using unfragmented packets ($1400$ bytes with the Don't Fragment flag set) and confirms that packets exceeding $1380$ bytes are dropped at the tunnel interface. Having verified the cause of the issue, which step should the analyst take next according to the CompTIA troubleshooting methodology?

A network technician is responding to connectivity issues reported by forklift operators in a distribution warehouse. The operators report that handheld Wi-Fi scanners frequently disconnect and fail to roam when driving deep into storage aisles. A wireless site survey indicates that while ceiling-mounted omnidirectional Access Points (APs) along the central walkway maintain strong signal strength of $-60\text{ dBm}$, the signal drops significantly to $-85\text{ dBm}$ inside the aisle rows filled with metallic racks and densely stacked inventory. Which of the following is the primary cause of this issue, and what is the most effective solution?

A network technician needs to trace an unlabeled copper UTP cable run from a wall jack in a user's office to its corresponding port on a patch panel in the telecommunications closet. Which of the following diagnostic tools is best suited for this task?

A network technician is troubleshooting a switch-to-switch trunk link that is dropping traffic. Reviewing the switch console logs reveals a native VLAN mismatch error, while interface statistics report high numbers of late collisions. Which TWO configuration actions should the technician take to resolve these issues? (Select TWO.)

A network administrator is troubleshooting host reachability issues on an enterprise dual-stack network. Workstations cannot connect to an internal server using its hostname `app.internal.example.com`, though direct IPv6 ping tests succeed. The administrator executes the following troubleshooting command from a client system:

C:\> nslookup app.internal.example.com
Server: dns01.internal.example.com
Address: 10.0.0.53

*** dns01.internal.example.com can't find app.internal.example.com: Non-existent domain

Next, the administrator runs `nslookup -type=AAAA app.internal.example.com`, which successfully returns the IPv6 address `2001:db8:85a3::8a2e:370:7334`.

Which of the following is the root cause of the initial resolution failure?

A network technician needs to inspect a newly terminated Category 6 UTP patch cable to confirm proper T568B pinout alignment and verify that there are no open or shorted conductor pairs. Which TWO of the following diagnostic tools are designed to verify conductor continuity and pinout arrangement on copper twisted-pair cables?

A network administrator installs a new set of IP phones on a dedicated voice VLAN (VLAN 40). The enterprise DHCP server resides on VLAN 10. The phones fail to obtain IP addresses and automatically configure APIPA addresses instead. Which TWO of the following resolution actions or diagnostic steps should the technician perform to troubleshoot and resolve this issue? (Select TWO)

A network engineer is troubleshooting a newly deployed 10GBASE-LR single-mode optical fiber link between two distribution switches spaced 2 kilometers apart. An optical power meter registers an excessive loss of $14\text{ dB}$ across the link, significantly exceeding the maximum insertion loss budget of $2.5\text{ dB}$, despite both transceiver end-face connectors passing visual inspection with a fiber microscope. Which diagnostic tool should the engineer utilize to measure reflections and pinpoint the precise location and cause of the attenuation fault along the fiber run?

Match each command-line network utility on the left with its primary diagnostic function on the right.