Troubleshooting practice questions

The network connection

Why it fails: A network connection is irrelevant when the machine shows no power, since link negotiation requires an energised NIC and running firmware. Checking it is tempting because network faults commonly cause boot-time errors, yet here the failure precedes POST, so physical power delivery must be verified first.

The operating system version

Why it fails: An operating system version cannot be queried on a machine that receives no power, so it cannot be the first check. It is tempting because OS version matters for compatibility and update troubleshooting once a system boots, but power-on faults must be traced through PSU, cabling and POST first.

The amount of free disk space

Why it fails: Free disk space cannot prevent power-on; a machine with a full disk still POSTs. It is tempting because disk capacity causes boot failures, but only after power-on, so checking power supply, cabling, and POST beep codes comes first.

Ring

Why it fails: Ring topology passes data token-style around a single closed loop, so one break or node failure can disrupt the whole segment; a small office sharing files needs a central switch, making star the efficient fit. Ring suits token-passing networks where deterministic access matters.

Bus

Why it fails: A bus topology shares one backbone cable, so a single break or fault disrupts every connected device, and performance degrades as collisions rise with each added node. It suits small, temporary or legacy coaxial networks where cost matters and few devices connect. Here, the building's employees need reliable, scalable file sharing, which a star topology's central switch provides.

Mesh

Why it fails: Mesh requires every node to interconnect directly, so a small office LAN would need cabling or wireless links between all endpoints, multiplying cost and configuration effort for no gain. It is tempting because mesh delivers path redundancy and fault tolerance, making it the right choice for wide-area backbones or networks where a single link failure must not isolate sites.

Update the graphics driver

Why it fails: Graphics drivers govern display rendering and have no bearing on network interface configuration, IP addressing or link state, so the fault remains. It tempts when a recent driver update coincides with the symptom, but driver rollback is the correct step only for display artefacts, not connectivity loss.

Replace the router

Why it fails: Swapping the router replaces functioning hardware before any diagnostic evidence identifies it as faulty, and the real cause, such as a disabled NIC or wrong gateway, persists. It tempts when the whole network appears down, but router replacement is justified only after confirming the device itself fails its own tests.

Reinstall the operating system

Why it fails: Reinstalling the operating system destroys the user's configuration and data while leaving the actual connectivity fault, such as a failed DHCP lease or bad cable, undiagnosed. It tempts when the OS appears corrupted, but that is warranted only after hardware, link and IP-layer checks have been exhausted.

Install new software

Why it fails: Installing software is not a standard troubleshooting step.

Escalate to vendor immediately

Why it fails: Escalation is a later step after initial troubleshooting fails.

8.8.8.8

Why it fails: 8.8.8.8 sits in the public routable space as Google Public DNS, outside the RFC 1918 ranges 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. It is tempting because it is a well-known address technicians use for connectivity testing, but reachability does not make an address private.

203.0.113.5

Why it fails: 203.0.113.5 falls in 203.0.113.0/24, reserved by RFC 5737 for documentation examples, not RFC 1918 private addressing. It is tempting because reserved documentation ranges are non-routable on the public internet, but non-routability differs from private addressing, so it is not a private IPv4 address.

169.254.1.1

Why it fails: 169.254.1.1 lies in 169.254.0.0/16, the link-local range assigned by APIPA when DHCP fails, not an RFC 1918 private address. It is tempting because link-local addresses are non-routable and appear during troubleshooting, but the stem asks specifically for private IPv4 addressing.

The path rule for C:\Program Files is too broad.

Why it fails: A broad C:\Program Files path rule governs executables in that directory only; it cannot deny execution from D:\Apps. It is tempting because overly permissive path rules are a genuine AppLocker misconfiguration, but the fault here lies with the rule covering the custom application's own location.

The publisher rule is incorrect.

Why it fails: Publisher rules match signed binaries by certificate attributes; an incorrect publisher rule would affect only signed applications matching that certificate, not an unsigned custom app in D:\Apps. It is tempting because publisher rules are the recommended AppLocker approach for signed software, but they are irrelevant to this path-based failure.

The enforcement mode is set to Enforce, blocking all unlisted apps.

Why it fails: Enforce mode applies the configured rules rather than blocking everything unlisted; a rule permitting D:\Apps may simply be absent, which is why the app fails. It is tempting because AppLocker's enforcement modes govern whether rules are audited or applied, and Enforce is the correct setting once rules are validated.

Web browser

Why it fails: The browser renders HTML, runs client-side JavaScript and issues HTTP requests; server-side logic executes on the remote web or application server. The browser would be the answer if the question asked which component processes client-side scripting or displays the interface.

Local firewall

Why it fails: A local firewall filters inbound and outbound network traffic on the host; it never executes application code. It would be the correct component if the question concerned blocked ports or denied connections causing the application to be unreachable.

Operating system

Why it fails: The operating system manages hardware, processes and files; it hosts the runtime but does not itself execute the application's server-side business logic. It would be the answer if the question asked which component allocates CPU and memory to the web server process.

Incorrect default gateway

Why it fails: The gateway 192.168.2.1 is on the workstation's own subnet, so it is correctly configured; the fault is that 192.168.1.100 sits on a different subnet (192.168.1.0/24) unreachable without routing. An incorrect gateway applies when the configured address falls outside the host's subnet.

Incorrect subnet mask

Why it fails: The mask 255.255.255.0 is correct for a /24 network, so it does not cause the fault. The workstation sits in 192.168.2.0/24 while the server is in 192.168.1.0/24, and the gateway 192.168.2.1 cannot route there. An incorrect mask would be the cause only if the address and mask disagreed.

Duplicate IP address on the network

Why it fails: A duplicate IP would cause intermittent or complete loss of connectivity and ARP conflicts, but the configuration shows a valid unique address on 192.168.2.0/24. Duplicate addressing fits when the host intermittently drops connections or reports address-conflict errors, not a consistent cross-subnet failure.

Operating system kernel

Why it fails: The kernel is the core of the operating system, loaded by the bootloader after firmware initialisation completes, so it cannot initialise the hardware that must already be running to load it. It is tempting because it manages hardware once running, making it correct when asked what controls devices after boot.

Boot loader

Why it fails: A boot loader runs after firmware has already initialised the hardware, so it only locates and starts the kernel rather than performing that initialisation itself. It is tempting because it does load the operating system, making it the correct answer when the question asks what hands control from firmware to the OS.

Device driver

Why it fails: A device driver is software loaded by the running kernel to control a specific peripheral, so it cannot execute before any OS exists. It is tempting because drivers do initialise hardware, but only after boot, whereas firmware such as UEFI or BIOS performs power-on self-test and hands control to the bootloader.

Restart the computer

Why it fails: Unlikely to fix connectivity issues.

Replace the network cable

Why it fails: Only if physical connection is suspected.

Power cycle the router

Why it fails: More disruptive; try software checks first.

Operating system

Why it fails: An operating system is loaded by the BIOS boot process, so it cannot itself be the BIOS firmware that runs first. It is tempting because both manage hardware and provide low-level services, but the BIOS resides in ROM on the motherboard and executes before any OS is present.

Application software

Why it fails: BIOS is firmware — low-level code stored in ROM/flash that initialises hardware before any operating system loads; application software runs atop an OS. It is tempting because BIOS ships as software, but its pre-boot, hardware-initialisation role places it in firmware, not applications.

Device driver

Why it fails: A device driver is software that lets the operating system communicate with a specific hardware component, so it cannot be the firmware that initialises hardware before any OS loads. It is tempting because drivers also sit between software and hardware, but they load after the OS, whereas BIOS runs from motherboard firmware at power-on.

802.11g

Why it fails: 802.11g operates only in the congested 2.4 GHz band, so it cannot avoid the interference from the many neighbouring networks described. It is tempting because it is widely supported and backward compatible, but 802.11g would suit a legacy environment where 5 GHz capability is unavailable.

802.11n (Wi-Fi 4)

Why it fails: Wi-Fi 4 is even older and slower.

802.11ac (Wi-Fi 5)

Why it fails: Wi-Fi 5 is older and less efficient in crowded environments.

Device driver

Why it fails: Device drivers are installed within the operating system on disk to let it control hardware, not stored in a motherboard chip. The option is tempting because drivers do mediate hardware access and are the right thing to inspect when a specific peripheral fails after the system has already booted.

Application software

Why it fails: Application software runs on top of the operating system to perform user tasks, and is stored on disk, not on a motherboard chip. It is tempting because applications are the most visible software layer, and reinstalling one is the right fix when a specific program misbehaves rather than the boot process.

Operating system

Why it fails: The operating system is installed on mass storage and loaded into RAM during boot; the chip-held low-level software is firmware. It is tempting because the OS does govern booting, and repairing it is the correct action when boot files on disk are corrupted rather than the firmware chip.

The user lacks permissions to list the folder.

Why it fails: The user can list the folder, so list permission is demonstrably granted; lacking it would produce an access-denied error on listing itself. This is tempting because permission gaps commonly cause access failures, but the symptom here is confined to download, so the missing grant concerns the read or get action.

The Allow statement on list also allows downloads.

Why it fails: Allow on list grants only the list action; download requires a separate read or get permission, so this statement describes the fault rather than the cause. It is tempting because list and read are often granted together, but the exhibit shows list allowed while download is not.

The policy is malformed and causes an error.

Why it fails: A malformed policy would typically fail evaluation entirely, denying both listing and download; the user can list, so the policy parses and applies. Malformed-policy errors are tempting because they explain blanket access failures, but the exhibit shows partial success, pointing to a condition or action mismatch instead.

Filter unwanted network traffic

Why it fails: Traffic filtering is performed by firewalls, ACLs and security groups inspecting packets; DNS maps hostnames to IP addresses. It tempts candidates because DNS filtering services can block malicious domains, making DNS the correct answer when the requirement is blocking access to specific websites rather than resolving names.

Provide wireless network access

Why it fails: Wireless access is provided by access points and wireless controllers via SSIDs and radio configuration; DNS performs name-to-IP resolution. It tempts candidates because Wi-Fi connectivity problems also produce "no internet" symptoms, so wireless configuration would be the right focus when clients cannot associate with the WLAN at all.

Assign IP addresses to devices on the network

Why it fails: DHCP assigns IP addresses, leases and gateway details; DNS resolves hostnames to IP addresses, which is why local resources work but internet browsing fails. It tempts technicians because both are core network services delivered automatically, and DHCP is the correct answer when hosts lack addresses or cannot reach their gateway.

Translates domain names to IP addresses

Why it fails: That's DNS, often provided by the router but not a primary function.

Amplifies wireless signal

Why it fails: Signal amplification is the job of a wireless access point or range extender, not the routing function. It is tempting because consumer routers commonly integrate an access point, but the question asks about routing functions, and the router's own Wi-Fi radio is a separate component.

Converts ISP signal to digital

Why it fails: Converting the ISP signal to digital is modem functionality, which the stem already confirms is working. It is tempting because home routers and modems are frequently combined in one gateway device, but the conversion itself belongs to the modem stage, not the router.

Virtualization

Why it fails: Virtualization is about running multiple operating systems, not checking requirements.

File compression

Why it fails: Compression reduces file size for storage or transfer and does not govern whether a program executes. It is tempting because compressed installers must be extracted before use, but the technician verified hardware and OS minimums, which is compatibility checking, not decompression.

Encryption

Why it fails: Encryption protects data confidentiality and has no bearing on whether an application launches. It is tempting because encryption is a core security concept, and it would be the answer if the question concerned protecting files or network traffic rather than diagnosing startup failure against minimum requirements.

DNS

Why it fails: DNS resolves names to IP addresses and performs no loop prevention at Layer 2. It is tempting because DNS problems can cause apparent slowness, and it would be correct if the question asked which protocol translates hostnames for client connections.

NAT

Why it fails: NAT rewrites IP addresses and ports for traffic crossing network boundaries; it does not detect or block Layer 2 loops. It is tempting because NAT is commonly configured on routers, and it would be the right answer if the question asked how private addresses reach the internet.

DHCP

Why it fails: DHCP assigns IP addresses and other configuration to hosts; it has no role in detecting or blocking Layer 2 forwarding loops. It is tempting because DHCP is a familiar network service, and it would be the right answer if the question asked which protocol supplies addresses to clients automatically.

Octal

Why it fails: Octal groups bits in threes, which does not align with the 8-bit bytes of a 48-bit MAC address, so it is never used for them. It appears in file permission notation, such as chmod 755, not in hardware addressing.

Decimal

Why it fails: Decimal notation would express each byte as a value from 0 to 255, as in IPv4 addressing, but MAC addresses are conventionally shown in hexadecimal. Decimal is used for IPv4 octets, not for link-layer hardware addresses.

Binary

Why it fails: MAC addresses are written as six hexadecimal octets, such as 00:1A:2B:3C:4D:5E, because each byte maps cleanly to two hex digits. Binary would render 48 bits, which is unwieldy for technicians to read or transcribe accurately during troubleshooting.

Install MSXML6.

Why it fails: MSXML6 provides XML parsing libraries, not permission resolution, so it cannot clear an 'Access Denied' error raised when the installer writes to protected locations. It is tempting because legacy applications often require specific MSXML versions, making it the right fix when the error log names a missing XML component rather than a permissions failure.

Install .NET Framework 3.5.

Why it fails: .NET Framework 3.5 supplies runtime libraries for legacy code, not filesystem or registry permissions, so installing it leaves the 'Access Denied' condition unresolved. It is tempting because legacy installers frequently fail without that runtime, making it correct when the log cites a missing .NET dependency instead of denied access.

Upgrade the application to a newer version.

Why it fails: Upgrading the application replaces the software rather than resolving the permission problem, and it may not even exist for a legacy product. It would be correct where the vendor has released a build that officially supports Windows 10 and the current version is genuinely unsupported.