All practice questions

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?

During a post-incident audit at a branch office, a security analyst discovers that an unauthorized device successfully connected to the internal network by plugging into an unassigned Ethernet wall port. Further inspection reveals that all unassigned switchports remain administrative enabled in their default state on VLAN 1. Which of the following actions represents the best practice to harden these unassigned ports against unauthorized physical network access?

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?

Following a major power interruption at an off-site facility, a core router fails to initialize its IP protocol stack, rendering all in-band network interfaces completely unreachable. Which of the following access methods allows a network administrator to establish direct command-line interface (CLI) access to diagnose the device's boot process?

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 needs to apply an inbound extended Access Control List (ACL) on a router interface connected to the user subnet $192.168.1.0/24$ to secure access to a server located at $10.0.0.10$. The policy must enforce the following requirements:

1. Allow administrator workstation $192.168.1.50$ SSH access (TCP port 22) to the server.
2. Block host $192.168.1.100$ from accessing HTTP services (TCP port 80) on the server.
3. Allow all other hosts on the $192.168.1.0/24$ subnet to access HTTP services (TCP port 80) on the server.
4. Block all other unauthorized IP traffic.

Arrange the given ACL statements in the correct top-to-bottom processing sequence to enforce this security policy without rule shadowing.

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?

An enterprise security Operations center detects two distinct anomalous network activities. First, an external threat actor transmits forged requests to public time servers, causing heavy response traffic to flood an internal web server's public IP interface. Second, an internal rogue host answers local broadcast Link-Local Multicast Name Resolution (LLMNR) queries to redirect workstations to a fake login portal. Which of the following attack types and vectors are present in this scenario? (Select TWO)

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.)

A network administrator must implement a continuous telemetry solution to monitor interface bandwidth utilization and device CPU metrics on core switches located across a remote branch link. Company security policy dictates that all monitoring data must be protected against eavesdropping and unauthorized tampering while in transit. Which protocol and configuration level should the administrator select to meet these security and performance monitoring requirements?