All practice questions

A workstation on an enterprise network is unable to access internal network shares or the Internet. A network technician runs `ipconfig` on the command prompt and receives the following output:

IPv4 Address. . . . . . . . . . . . : 169.254.184.91
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . :

Which of the following is the most likely cause of this issue?

A network technician connects two switches, Switch-A and Switch-B, via an 802.1Q trunk link. Users on VLAN 10 connected to Switch-A cannot communicate with users on VLAN 10 attached to Switch-B. Console output on Switch-A displays `%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on interface GigabitEthernet0/1 (10), with Switch-B GigabitEthernet0/1 (1)`. Which TWO of the following statements correctly explain the network behavior and the required resolution?

A network technician is troubleshooting a laptop that was moved from an executive office to a newly created conference room VLAN. The laptop cannot access internal resources, and executing `ipconfig /all` displays an IPv4 address of $169.254.88.15$ with a subnet mask of $255.255.0.0$. Which of the following statements correctly identify the cause of this issue and the appropriate next diagnostic step? (Select TWO.)

A network engineer is troubleshooting performance degradation on an enterprise Storage Area Network (SAN) uplink. After analyzing link metrics and performing diagnostic tests, the engineer successfully confirms their hypothesis that excessive frame errors are caused by an over-subscribed switch interface. Which of the following is the NEXT step the engineer should take according to the CompTIA troubleshooting methodology?

A network technician replaces a damaged modular plug on a Category 6 UTP cable. A basic continuity test shows that all eight conductors line up end-to-end, but the network link suffers from severe Near-End Crosstalk (NEXT) and high packet loss. Which physical cabling mistake is the most likely cause of this issue?

Match each network performance monitoring metric or telemetry mechanism on the left with its corresponding operational impact or functional behavior on the right.

A network technician is troubleshooting an issue where a workstation fails to connect to an internal web application after a recent server migration. The technician executes two command-line utilities on the client workstation and receives the following output:

C:\> nslookup portal.company.local
Server: dns01.company.local
Address: 10.10.5.2

Name: portal.company.local
Address: 10.10.20.100

C:\> ping portal.company.local
Pinging portal.company.local [10.10.5.50] with 32 bytes of data:
Request timed out.

Based on the diagnostic output, which of the following is the most likely cause of this discrepancy?

A client workstation on VLAN 10 ($192.168.10.45/24$) cannot reach a database server located on VLAN 30 ($10.0.30.100/24$) across an enterprise Layer 3 switch with Access Control Lists (ACLs). Following the CompTIA network troubleshooting methodology, place the diagnostic and remediation actions in the correct sequential order from first step to last step.

A network administrator is securing a newly deployed edge router at a remote facility. The organization requires central monitoring of system health over public networks while enforcing payload encryption and cryptographic user authentication. Additionally, legacy unencrypted protocols must be removed. Which configuration strategy best satisfies these hardening requirements for network monitoring?

A user's workstation is assigned the static IP address $192.168.10.45$ with a subnet mask of $255.255.255.0$ (/24). The user can successfully communicate with other devices on the local subnet, but cannot access any remote subnets or external websites. Running diagnostic checks shows that the workstation's default gateway is configured as $192.168.20.1$. Which of the following is the root cause of the gateway connectivity failure?

A network engineer provisions a new subinterface `GigabitEthernet0/0.40` on a branch router to serve an isolated IoT subnet ($172.16.40.0/24$). Devices connected to VLAN 40 are unable to reach external resources and auto-assign link-local IPv4 addresses in the $169.254.x.x$ range. A terminal capture on the router shows the following configuration:

text
interface GigabitEthernet0/0.10
description Corporate_Users
encapsulation dot1Q 10
ip address 172.16.10.1 255.255.255.0
ip helper-address 10.10.10.50
!
interface GigabitEthernet0/0.40
description IoT_Devices
encapsulation dot1Q 40
ip address 172.16.40.1 255.255.255.0

Existing client workstations on `GigabitEthernet0/0.10` receive leases dynamically from the central DHCP server at $10.10.10.50$ without issue. Which configuration change on the branch router will resolve the IP addressing failure for VLAN 40?

A network administrator has confirmed through diagnostic testing that an outdated firmware version on a core distribution switch caused intermittent BGP route flapping. Having confirmed this theory, the administrator is now preparing to execute the 'Establish a plan of action to resolve the problem and identify potential effects' step in the CompTIA troubleshooting methodology. Which of the following specific tasks should be conducted as part of this step? (Select TWO)

A network technician is provisioning an isolated Wi-Fi network for temporary contractors at a branch office. The organization requires protection against offline dictionary attacks and passive eavesdropping, but explicitly wants to avoid the operational complexity of deploying an 802.1X RADIUS server or digital certificates. Which wireless security standard and authentication mechanism best meets these specifications?

A network administrator is configuring an extended IPv4 Access Control List (ACL) on a gateway router to secure a DMZ web server at IP address $10.80.1.20/24$. The security policy requires allowing inbound web traffic (HTTPS) from any external source, and allowing remote administration (SSH) strictly from the internal network management subnet ($172.16.50.0/24$). All other inbound traffic must be blocked. Which TWO of the following extended ACL statements must be included to satisfy these requirements? (Select TWO)

A network administrator is troubleshooting an issue where internal workstations on subnet $10.10.10.0/24$ cannot access a web server at $10.10.50.25/24$ using HTTPS. Upon inspecting the inbound Access Control List (ACL) on the destination interface, the administrator views the following configuration:

text
access-list 105 permit tcp 10.10.10.0 0.0.0.255 host 10.10.50.25 eq 80
access-list 105 deny ip any host 10.10.50.25
access-list 105 permit tcp 10.10.10.0 0.0.0.255 host 10.10.50.25 eq 443

Which of the following describes the root cause of the connection failure?

A network administrator is troubleshooting an issue where database servers deployed on a new broadcast domain (VLAN 104, $10.104.0.0/22$) fail to acquire dynamic IPv4 addresses and assign themselves $169.254.x.x$ addresses instead. A packet capture on the local router subinterface `GigabitEthernet0/0.104` shows incoming broadcast DHCP DISCOVER frames from clients, but no DHCP OFFER packets return. The central DHCP server is located on VLAN 10 ($10.10.10.2$). The configuration of the local subinterface is as follows:

interface GigabitEthernet0/0.104
encapsulation dot1Q 104
ip address 10.104.0.1 255.255.252.0

Which of the following actions should the network administrator perform to resolve this issue and enable dynamic address assignment for clients in VLAN 104? (Select TWO.)

A network administrator attempts to force Switch-B to become the primary Spanning Tree Protocol (STP) root bridge for VLAN 10 during an upcoming maintenance window. The administrator executes the CLI command `spanning-tree vlan 10 priority 61440` on Switch-B. After taking the existing core switch offline, host traffic experiences unexpected latency, and diagnostic logs reveal that Switch-C—which has a default configuration—was elected root bridge instead of Switch-B. Switch-C has an STP priority of 32768 for VLAN 10. Which of the following explains why Switch-C became the root bridge instead of Switch-B?

A network administrator is troubleshooting a client workstation that receives a name resolution error when attempting to reach an internal portal at `hrportal.contoso.com`. In what sequence should the administrator execute the following steps to systematically isolate the issue according to standard operating system name resolution precedence?

A network administrator is troubleshooting an issue where a client workstation cannot reach an internal database server located at $172.28.15.100$. The administrator collects the host settings and router interface details:

Host Settings:
- IP Address: $10.50.10.45$
- Subnet Mask: $255.255.255.192$ ($/26$)
- Default Gateway: $10.50.10.65$

Router Interface (GigabitEthernet0/0) & Inbound ACL:
- Interface IP: $10.50.10.1/26$
- Applied Inbound Access Control List:
- `line 10: permit tcp 10.50.10.0 0.0.0.63 host 172.28.15.100 eq 3306`
- `line 20: deny ip any any`

Which TWO of the following issues are directly preventing or obstructing successful communication and verification between the workstation and the database server?

A network technician is investigating intermittent connectivity and framing errors on a trunk link between two distribution switches. The technician has established a theory that a native VLAN mismatch is causing untagged traffic to drop and has confirmed this cause by inspecting packet captures on both switch interfaces. According to the CompTIA troubleshooting methodology, which of the following actions should the technician take NEXT?