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CIoTSP practice questions

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Question 1IoT Architecture and Security Fundamentals

In the IoT reference model, which layer is primarily responsible for converting raw sensor readings into normalized, standardized data formats before transmission?

  1. Edge (perception) layer Correct answer.
  2. Network transport layer
  3. Application layer
  4. Business process layer

Explanation

The edge or perception layer contains the devices and gateways closest to the physical world, and it typically performs local data normalization, filtering, and format conversion before data leaves the device. Higher layers consume standardized data rather than raw sensor signals, so normalization at the edge reduces bandwidth and improves interoperability.

Question 2IoT Architecture and Security Fundamentals

A smart-building deployment uses constrained devices that must send small telemetry payloads over UDP with minimal overhead. Which protocol best matches these constraints?

  1. HTTPS with TLS
  2. SFTP
  3. MQTT over TCP
  4. CoAP Correct answer.

Explanation

CoAP is a lightweight request/response protocol designed for constrained nodes and networks, built on UDP with compact binary headers and optional DTLS for security. MQTT and HTTPS both rely on TCP, and SFTP is a file transfer protocol unsuitable for frequent small telemetry messages.

Question 3IoT Architecture and Security Fundamentals

Which statement best describes the difference between authentication and authorization in an IoT platform?

  1. Authentication determines resource access; authorization verifies identity.
  2. Authentication applies only to users; authorization applies only to devices.
  3. Both terms describe the same access-control decision made at the gateway.
  4. Authentication verifies identity; authorization determines which resources that identity may access. Correct answer.

Explanation

Authentication establishes who or what is presenting credentials, while authorization evaluates policy to decide what that authenticated principal is permitted to do. Keeping the two separate lets a platform confirm a device identity and then apply role or attribute policies independently.

Question 4IoT Architecture and Security Fundamentals

An IoT security architect wants each device to prove possession of a private key without transmitting a shared secret. Which mechanism accomplishes this?

  1. Public key challenge-response authentication Correct answer.
  2. MAC address filtering
  3. Static password login
  4. Pre-shared key exchange

Explanation

In challenge-response with public key cryptography, the verifier sends a nonce that the device signs with its private key, proving possession without revealing the key. Pre-shared keys and passwords require transmitting or storing a shared secret, and MAC filtering is trivially spoofable.

Question 5IoT Architecture and Security Fundamentals

What is the primary security purpose of segmenting an IoT network from the corporate IT network?

  1. To reduce the cost of cloud connectivity
  2. To increase the bandwidth available to sensors
  3. To limit the blast radius if a compromised device attempts lateral movement Correct answer.
  4. To simplify firmware update delivery

Explanation

Network segmentation places IoT devices in a separate zone with controlled traffic flows, so a compromised device cannot freely reach corporate systems. This containment limits lateral movement and reduces the impact of an incident.

Question 6IoT Architecture and Security Fundamentals

Which data state is addressed by encrypting telemetry at rest in an IoT cloud time-series database?

  1. Data in use
  2. Data in transit
  3. Data in motion
  4. Data at rest Correct answer.

Explanation

Data at rest refers to stored data, such as records held in a database or on disk, and encryption at rest protects that stored form. Data in transit or motion covers network transmission, and data in use refers to data being processed in memory.

Question 7IoT Architecture and Security Fundamentals

Which characteristic is a defining property of a botnet used in large-scale IoT attacks?

  1. Each infected device is individually managed by a human operator.
  2. The botnet only functions on a single local network segment.
  3. Many compromised devices are remotely coordinated to act in concert. Correct answer.
  4. The devices must all run full desktop operating systems.

Explanation

A botnet is a collection of compromised devices, often IoT gear with weak credentials, controlled remotely by an attacker to perform coordinated actions such as distributed denial of service. Coordination across many hosts is the defining feature.

Question 8IoT Architecture and Security Fundamentals

What role does a device identity certificate issued by a private certificate authority serve in an IoT PKI?

  1. It stores the device's private key on the server.
  2. It encrypts the device firmware image.
  3. It binds a device's public key to its identity so peers can verify it. Correct answer.
  4. It replaces the need for any access-control policy.

Explanation

An X.509 certificate signed by a trusted CA binds a public key to a subject identity, allowing relying parties to verify the device's authenticity through the CA trust chain. The private key stays on the device and access policy is still required.

Question 9IoT Architecture and Security Fundamentals

A deployment uses LoRaWAN for low-power wide-area connectivity. Which architectural consideration most directly affects security design?

  1. Devices communicate only over Ethernet.
  2. All devices share a single global encryption key.
  3. The network server has no role in key management.
  4. The gateway relays frames, so end-to-end payload protection must be provided above the link. Correct answer.

Explanation

In LoRaWAN the gateway forwards frames to a network server, so the radio link alone does not guarantee end-to-end confidentiality between device and application. Architects therefore rely on application-layer keys and payload encryption to protect data across the relay path.

Question 10IoT Architecture and Security Fundamentals

An MQTT deployment must prevent an eavesdropper on the network from reading published payloads. Which control directly addresses this?

  1. Disabling the retained message flag
  2. Setting a longer keepalive interval
  3. Using TLS on the broker connection Correct answer.
  4. Increasing the QoS level

Explanation

MQTT itself does not encrypt payloads, so confidentiality on the wire requires a TLS-protected connection between clients and broker. Keepalive, retained flags, and QoS affect delivery behavior and liveness, not confidentiality.

Question 11IoT Architecture and Security Fundamentals

A fleet of sensors shares one symmetric key embedded in firmware. What is the most significant architectural weakness of this design?

  1. The key cannot be used with AES.
  2. Symmetric keys cannot be rotated.
  3. The key increases device power consumption.
  4. Compromise of one device exposes the entire fleet's communications. Correct answer.

Explanation

A single shared key embedded in firmware means extracting it from any one device compromises the confidentiality of all devices using that key. Per-device keys or unique credentials limit the blast radius of a single compromise.

Question 12IoT Architecture and Security Fundamentals

Which practice best mitigates the risk of IoT devices shipping with default administrative credentials?

  1. Relying on the user to change the password eventually
  2. Allowing default credentials until the first reboot
  3. Publishing a common default password in the manual
  4. Forcing a unique credential or certificate per device at manufacturing time Correct answer.

Explanation

Requiring unique per-device credentials or certificates at provisioning removes the shared default that attackers exploit at scale. Defaults that persist until user action leave a large vulnerable window.

Question 13IoT Architecture and Security Fundamentals

A gateway aggregates data from many sensors and forwards it to the cloud. Which security function is most appropriate to place at the gateway?

  1. Enforcing local policy and filtering outbound traffic to the cloud Correct answer.
  2. Disabling encryption to reduce latency
  3. Storing the cloud root CA private key
  4. Terminating all device authentication and issuing cloud credentials to sensors

Explanation

A gateway is well positioned to enforce local security policy, filter or rate-limit outbound traffic, and broker device-to-cloud communication. It should not become a single point that hands out cloud credentials or holds the CA private key.

Question 14IoT Architecture and Security Fundamentals

An organization wants to detect anomalous behavior from a compromised IoT device already inside the network. Which control provides the most direct capability?

  1. Network traffic monitoring with behavioral baselines Correct answer.
  2. Static firewall rules allowing all outbound traffic
  3. Full-disk encryption on servers
  4. Password complexity policy on user accounts

Explanation

Behavioral monitoring compares device traffic against a learned baseline, so deviations such as unexpected destinations or volumes can reveal compromise. Static allow-all rules, password policy, and disk encryption do not detect in-network device anomalies.

Question 15IoT Architecture and Security Fundamentals

Which threat is most directly mitigated by secure boot on an IoT device?

  1. Denial of service from a flood of network packets
  2. Weak Wi-Fi signal strength
  3. Physical theft of the device
  4. Persistent malware replacing the bootloader or firmware Correct answer.

Explanation

Secure boot uses cryptographic signatures to verify each stage of the boot chain, preventing unauthorized firmware or bootloader replacement from executing. It does not address network flooding, physical theft, or radio signal quality.

Question 16IoT Architecture and Security Fundamentals

A system uses OTA updates for thousands of devices. Which control most directly preserves firmware integrity during distribution?

  1. Compressing the firmware image before sending
  2. Signing the firmware and verifying the signature on the device Correct answer.
  3. Sending updates only during off-peak hours
  4. Using UDP for faster transfer

Explanation

Digital signatures over the firmware allow each device to verify authenticity and integrity before applying the update, defeating tampered images. Compression, scheduling, and transport choice do not by themselves provide integrity assurance.

Question 17IoT Architecture and Security Fundamentals

Which access-control model is most natural for enforcing that a device may publish only to topics matching its own identifier?

  1. Mandatory access control with fixed labels
  2. Role-based access control with a single shared role
  3. Discretionary access control owned by the device
  4. Attribute-based policy keyed to the device identity Correct answer.

Explanation

Attribute-based policy can evaluate the authenticated device identity against the requested topic, enforcing per-device least privilege at scale. A single shared role cannot express per-device topic restrictions.

Question 18IoT Architecture and Security Fundamentals

Why is certificate revocation important in a large IoT PKI?

  1. It increases the key length of certificates.
  2. It renews certificates before expiration.
  3. It allows a compromised or retired device certificate to be rejected before expiry. Correct answer.
  4. It encrypts certificate contents.

Explanation

Revocation, via CRL or OCSP, lets relying parties reject certificates that should no longer be trusted, such as those from compromised or decommissioned devices. Without it, a stolen device certificate remains valid until expiration.

Question 19IoT Architecture and Security Fundamentals

An architect must choose between storing device secrets in plain flash versus a hardware secure element. Which argument best supports the secure element?

  1. It removes the requirement for firmware signing.
  2. It provides isolated key storage and cryptographic operations resistant to extraction. Correct answer.
  3. It guarantees the device never loses power.
  4. It eliminates the need for device authentication.

Explanation

A secure element stores keys in tamper-resistant hardware and performs crypto operations internally, so keys are not exposed in general memory or flash. It complements, rather than replaces, authentication and firmware signing.

Question 20IoT Architecture and Security Fundamentals

Which combination best represents defense in depth for an IoT deployment?

  1. Relying solely on device passwords
  2. A single strong perimeter firewall protecting all devices
  3. Layered controls including device hardening, segmentation, monitoring, and encryption Correct answer.
  4. Encrypting only the cloud database

Explanation

Defense in depth layers independent controls so failure of one does not expose the whole system. Device hardening, network segmentation, monitoring, and encryption each address different attack paths.

Question 21IoT Architecture and Security Fundamentals

A device manufacturer must prove that firmware running on a device is the version it published. Which mechanism provides this attestation?

  1. A signed measurement of firmware hash reported via a trusted root Correct answer.
  2. A timestamp from the device clock
  3. A DNS lookup of the update server
  4. A random session token

Explanation

Remote attestation relies on a hardware root of trust to measure firmware and sign the resulting hash, allowing a verifier to confirm the running image matches the published version. Tokens, DNS, and clock timestamps do not attest to firmware integrity.

Question 22IoT Architecture and Security Fundamentals

An attacker replays captured sensor commands to a device. Which design change most effectively prevents the replay from succeeding?

  1. Increasing the command send rate
  2. Compressing command payloads
  3. Including a monotonically increasing counter or nonce validated by the device Correct answer.
  4. Encrypting the command with a static key and no freshness value

Explanation

Freshness values such as monotonic counters or nonces let the device reject previously seen messages, defeating replay. Encryption without freshness still permits an attacker to resend a valid ciphertext.

Question 23IoT Architecture and Security Fundamentals

A zero-trust architecture is applied to an IoT fleet. Which principle most characterizes this approach?

  1. Devices inside the trusted LAN are implicitly authorized.
  2. Only the cloud perimeter enforces access decisions.
  3. Every request is authenticated and authorized regardless of network location. Correct answer.
  4. Devices are trusted after a single successful login.

Explanation

Zero trust removes implicit trust based on network position and requires continuous authentication and authorization for each request. Being on an internal LAN or having logged in once does not confer lasting trust.

Question 24IoT Architecture and Security Fundamentals

A gateway performs protocol translation between a proprietary field bus and MQTT. Which risk does this translation layer introduce?

  1. It can become a trust boundary where malformed or unauthorized commands cross between protocols. Correct answer.
  2. It eliminates the need for device identity.
  3. It guarantees end-to-end encryption.
  4. It reduces the number of attack surfaces.

Explanation

Protocol translation creates a boundary where data and commands are reinterpreted, so validation and authorization must be enforced there to prevent malformed or unauthorized commands from crossing. It adds rather than removes attack surface and does not provide encryption or identity by itself.

Question 25IoT Architecture and Security Fundamentals

An organization must protect data processed inside a cloud analytics service that computes on sensitive telemetry. Which technique addresses confidentiality during computation?

  1. Segmenting the network into VLANs
  2. Hashing the telemetry before ingestion
  3. Confidential computing with hardware-isolated enclaves Correct answer.
  4. Encrypting the data only while stored on disk

Explanation

Confidential computing uses hardware-isolated enclaves so data remains protected while being processed, covering the data-in-use state. Disk encryption, hashing, and VLAN segmentation do not protect data during computation.

Question 26IoT Architecture and Security Fundamentals

In a reference IoT architecture, which layer is responsible for normalizing heterogeneous sensor protocols before data reaches cloud analytics services?

  1. The business application layer
  2. The physical sensing layer
  3. The device firmware bootloader
  4. The edge or gateway layer Correct answer.

Explanation

Edge and gateway tiers sit between constrained field devices and cloud services, so they are the natural place to translate proprietary field buses and normalize payload formats. The sensing layer only produces raw measurements, and application services consume already-normalized data.

Question 27IoT Architecture and Security Fundamentals

Which statement best describes the security significance of the constrained device tier in an IoT architecture?

  1. Devices often lack resources for strong cryptography and are physically accessible to attackers Correct answer.
  2. Devices always run full general-purpose operating systems with host firewalls
  3. Devices typically hold the longest-lived credentials in the deployment
  4. Devices are isolated from the network and therefore need no authentication

Explanation

Constrained devices commonly have limited CPU, memory, and energy budgets, which restricts cryptographic options, and they are frequently deployed in physically reachable locations. That combination makes them the weakest and most exposed tier in most deployments.

Question 28IoT Architecture and Security Fundamentals

An architecture routes all device traffic through a broker that enforces per-device topic permissions. Which design goal does this placement most directly serve?

  1. Eliminating the need for transport encryption between devices and the broker
  2. Centralizing authorization decisions so individual devices need not implement complex policy Correct answer.
  3. Replacing device identity certificates with shared passwords
  4. Guaranteeing firmware integrity on each connected device

Explanation

A broker acting as a policy enforcement point lets the architecture apply consistent authorization rules in one place, which suits constrained devices that cannot run rich policy engines. It complements, but does not replace, transport encryption, firmware verification, or strong device identity.

Question 29IoT Architecture and Security Fundamentals

A hospital deploys wearable patient monitors on a segmented clinical network. Which architectural control most directly limits lateral movement if one monitor is compromised?

  1. Microsegmentation restricting each monitor to only its required destination endpoints Correct answer.
  2. Placing all monitors and clinical workstations in one flat VLAN
  3. Logging all monitor traffic to a central SIEM without filtering
  4. A longer Wi-Fi pre-shared key rotated every quarter

Explanation

Microsegmentation enforces least-privilege network paths so a compromised monitor can reach only the endpoints its function requires, which blocks lateral movement toward other clinical systems. Logging alone detects but does not contain, and a flat VLAN increases exposure.

Question 30IoT Architecture and Security Fundamentals

An architect must choose between a cloud-hosted broker and an on-premises broker for a factory whose control loops tolerate only a few milliseconds of added latency. Which trade-off analysis is most sound?

  1. On-premises brokering removes the need for device authentication inside the plant
  2. On-premises brokering reduces round-trip latency and keeps control traffic local, while cloud brokering simplifies fleet-wide management at the cost of WAN latency Correct answer.
  3. The choice has no security consequence because brokers never handle credentials
  4. Cloud brokering always lowers latency because hyperscalers have faster CPUs than factory servers

Explanation

Latency-sensitive control loops favor local brokering because traffic avoids WAN round trips, and keeping control messages on-premises also reduces exposure. Cloud brokering offers centralized management and elasticity, but those benefits come with added network latency that tight control loops cannot absorb.

Question 31IoT Device Security and Hardening

A technician is commissioning a fleet of IoT sensors that must prove their identity to a cloud broker using certificates burned in at manufacture. Which mechanism best describes what the sensors are using?

  1. OAuth 2.0 bearer token authentication
  2. X.509 client certificate authentication Correct answer.
  3. Pre-shared key authentication
  4. SAS token authentication

Explanation

X.509 client certificates let a device present a cryptographic identity that the broker validates against a trusted certificate authority, which is the standard way to bind a manufactured identity to a device. Pre-shared keys and bearer tokens do not carry a signed public-key identity, and SAS tokens are time-limited shared secrets rather than device certificates.

Question 32IoT Device Security and Hardening

An engineer must ensure firmware on constrained IoT devices cannot be modified without detection even if an attacker gains write access to flash storage. Which control directly provides this property?

  1. Storing the firmware image in a read-only partition
  2. Encrypting the firmware image with a symmetric key
  3. Signing the firmware image and verifying the signature before boot Correct answer.
  4. Compressing the firmware image to reduce flash usage

Explanation

A digital signature over the firmware lets the bootloader detect any modification, because an attacker cannot produce a valid signature without the private signing key. Encryption alone hides contents but does not prove integrity, and read-only partitions can often be bypassed at the hardware or bootloader level.

Question 33IoT Device Security and Hardening

Which practice most effectively reduces the attack surface of an IoT device before it ships?

  1. Using the default vendor administrator password
  2. Disabling unused services, ports, and debug interfaces Correct answer.
  3. Broadcasting the device model in every network packet
  4. Enabling a Telnet service for field diagnostics

Explanation

Attack surface reduction means removing or disabling every unnecessary service, port, and debug path so there is less for an adversary to exploit. Leaving diagnostics open, keeping default credentials, or over-sharing device details all increase exposure rather than reduce it.

Question 34IoT Device Security and Hardening

A device stores a unique symmetric key used to authenticate to a backend. Which storage approach best protects that key against extraction by an attacker with physical access?

  1. Hard-coded in the compiled application binary
  2. Plaintext in a configuration file on the filesystem
  3. In an environment variable set at boot
  4. Inside a hardware secure element or TPM Correct answer.

Explanation

A secure element or TPM is designed to hold keys in protected hardware so they cannot be read out directly, and cryptographic operations happen inside the boundary. Configuration files, compiled binaries, and environment variables are all readable by an attacker who gains code execution or physical access.

Question 35IoT Device Security and Hardening

Which change most directly mitigates the risk of an attacker using a JTAG interface to read device memory?

  1. Increasing the device's Wi-Fi transmit power
  2. Rotating the device's cloud API credentials
  3. Disabling or locking the debug port in production firmware and fuses Correct answer.
  4. Enabling verbose logging to a remote server

Explanation

JTAG and similar debug interfaces give direct access to memory and processor control, so production devices should disable or permanently lock them via fuses or boot configuration. Radio settings, credential rotation, and remote logging do not affect physical debug access.

Question 36IoT Device Security and Hardening

An operations team wants each IoT device to have credentials that are unique and revocable without reflashing the entire fleet. Which provisioning approach best meets this requirement?

  1. Per-device certificates enrolled through a secure provisioning service Correct answer.
  2. A shared password written on a label on each device
  3. A global API key stored in the cloud console
  4. A single shared device key compiled into all firmware

Explanation

Per-device certificates issued through a provisioning service give each device a distinct identity that can be revoked individually in the certificate authority. Shared keys, shared passwords, and global API keys cannot be revoked for one device without affecting the whole fleet.

Question 37IoT Device Security and Hardening

Which configuration on an IoT device best limits the impact of a compromised local network service?

  1. Running the service under a least-privilege account with a restricted sandbox Correct answer.
  2. Disabling all logging for the service
  3. Running the service as root with full filesystem access
  4. Allowing the service to accept connections from any source address

Explanation

Least privilege and sandboxing confine what a compromised service can do, limiting lateral movement and data access. Running as root, disabling logging, and accepting any source all expand the blast radius or reduce detection.

Question 38IoT Device Security and Hardening

What is the primary security purpose of verifying a firmware update package's signature on the device before applying it?

  1. To reduce the download size of the update
  2. To confirm the update is compatible with the device's radio
  3. To ensure the update originated from a trusted source and was not altered Correct answer.
  4. To speed up the flashing process

Explanation

Signature verification establishes authenticity and integrity, so the device only installs firmware produced by the trusted signer and unchanged in transit. Size, flashing speed, and radio compatibility are unrelated to the cryptographic guarantee.

Question 39IoT Device Security and Hardening

A company deploys IoT cameras that ship with a default password printed on the box. Which action should be taken during onboarding to align with common hardening guidance?

  1. Store the default password in a public support wiki
  2. Keep the default password so field staff can always log in
  3. Require the password to be changed on first use before the device becomes operational Correct answer.
  4. Use the same default password across all sites for consistency

Explanation

Forcing a unique credential change on first use eliminates the well-known default password that attackers routinely try. Retaining, publishing, or standardizing the default password preserves the exposure.

Question 40IoT Device Security and Hardening

An architect must prevent an attacker who captures network traffic from replaying a previously valid command to an IoT actuator. Which design element addresses this?

  1. Encrypting the command payload with AES-CBC
  2. Including a monotonically increasing nonce or timestamp that the receiver validates Correct answer.
  3. Compressing the command before transmission
  4. Sending the command over UDP instead of TCP

Explanation

Replay protection requires the receiver to reject commands it has already seen, which a monotonic nonce or validated timestamp provides. Encryption alone can be replayed verbatim, and compression or transport choice does not bind a message to freshness.

Question 41IoT Device Security and Hardening

A device's bootloader checks the firmware signature but then loads an unsigned kernel module at runtime. Which weakness does this represent?

  1. A broken chain of trust due to an unverified runtime component Correct answer.
  2. A key rotation failure in the certificate authority
  3. A complete secure boot chain
  4. A denial-of-service vulnerability in the bootloader

Explanation

Secure boot must establish a continuous chain of trust from the root of trust through every loaded component; an unsigned runtime module breaks that chain. The signature check on the initial firmware does not extend automatically to later loads, and this is an integrity gap rather than a DoS or CA rotation issue.

Question 42IoT Device Security and Hardening

A security team wants to detect if a deployed IoT device's firmware has been tampered with after installation. Which approach provides ongoing assurance?

  1. Periodically rebooting the device
  2. Measuring firmware hashes at boot and reporting them to a remote attestation service Correct answer.
  3. Relying on the vendor's release notes
  4. Increasing the device's logging verbosity

Explanation

Remote attestation compares boot-time measurements against known-good values so the backend can detect unauthorized firmware changes. Release notes, reboots, and logging do not independently verify firmware integrity.

Question 43IoT Device Security and Hardening

An engineer is hardening a Linux-based IoT gateway. Which combination best reflects a defense-in-depth approach to local privilege escalation?

  1. Enabling root SSH login and using a shared operator account
  2. Running all services as root to simplify permission management
  3. Removing unnecessary setuid binaries, enforcing mandatory access control, and patching the kernel Correct answer.
  4. Disabling the firewall and enabling passwordless sudo for operators

Explanation

Defense in depth layers independent controls: minimizing setuid binaries removes escalation paths, mandatory access control confines processes, and kernel patching closes known vulnerabilities. The other combinations deliberately weaken privilege boundaries.

Question 44IoT Device Security and Hardening

A product team wants to prevent an attacker from downgrading a device to an older firmware version with a known vulnerability. Which control should be implemented?

  1. Compressing firmware images
  2. Enforcing a minimum allowed firmware version or anti-rollback counter Correct answer.
  3. Encrypting firmware with a public key
  4. Using a larger flash memory chip

Explanation

Anti-rollback enforcement, often via a monotonic version counter in secure storage, prevents installation of older vulnerable firmware even if it is validly signed. Compression, encryption, and larger flash do not restrict which versions may run.

Question 45IoT Device Security and Hardening

An IoT deployment must protect data at rest on a device that may be physically stolen. Which approach best protects the confidentiality of stored sensor data?

  1. Encrypting the data with keys held in a hardware root of trust Correct answer.
  2. Storing data in plaintext with file permissions set to read-only
  3. Compressing the data before storage
  4. Renaming the data files to obscure their purpose

Explanation

Encryption with keys protected by a hardware root of trust keeps stored data confidential even when the device is in an attacker's hands, because the key is not extractable. Permissions, renaming, and compression do not withstand physical access.

Question 46IoT Device Security and Hardening

A network architect wants to isolate IoT devices so a compromised sensor cannot reach corporate servers. Which control most directly achieves this segmentation?

  1. Using the same subnet for IoT and corporate workstations
  2. Enabling a guest Wi-Fi SSID with no client isolation
  3. Placing IoT devices on a dedicated VLAN with restrictive firewall rules to other zones Correct answer.
  4. Assigning all devices public IP addresses

Explanation

A dedicated VLAN combined with firewall rules that only permit required flows enforces segmentation so a compromised device cannot freely reach sensitive systems. Public addressing, non-isolated guest networks, and shared subnets all increase reachability.

Question 47IoT Device Security and Hardening

A device vendor wants to ensure that only authorized devices can connect to its MQTT broker. Which broker-side control is most appropriate?

  1. Allowing anonymous connections to simplify onboarding
  2. Disabling authentication and relying on obscure topic names
  3. Requiring mutual TLS with client certificates validated against a trusted CA Correct answer.
  4. Using a single shared username and password for all devices

Explanation

Mutual TLS requires each device to present a certificate that the broker validates, giving per-device authentication. Anonymous access, obscure topics, and shared credentials do not establish which device is connecting and are easily abused.

Question 48IoT Device Security and Hardening

A security analyst reviews a device's configuration and finds that its web management interface uses HTTP with a self-signed certificate replaced by plaintext. Which change most directly protects administrator credentials in transit?

  1. Increasing the interface's session timeout
  2. Restricting the interface to IPv6 only
  3. Enabling HTTPS with a properly validated certificate and disabling plain HTTP Correct answer.
  4. Adding a CAPTCHA to the login page

Explanation

Transport encryption with a validated certificate prevents eavesdropping and man-in-the-middle interception of administrator credentials. Session timeouts, CAPTCHAs, and address family restrictions do not encrypt the login exchange.

Question 49IoT Device Security and Hardening

A firmware team must ensure that a compromised build server cannot silently ship malicious firmware to customers. Which control best addresses this?

  1. Publishing firmware hashes only in release emails
  2. Storing the signing key on the build server for convenience
  3. Disabling signature verification to speed up releases
  4. Signing firmware with a key held offline or in an HSM separate from the build server Correct answer.

Explanation

Separating the signing key from the build environment means a compromised build server cannot produce validly signed malicious firmware. Keeping the key on the build server, disabling verification, or relying on informal hash publication removes that protection.

Question 50IoT Device Security and Hardening

An engineer observes that a deployed sensor accepts unsigned configuration updates over the local network. Which risk is most directly introduced?

  1. Reduced wireless range
  2. Increased power consumption during updates
  3. An attacker on the local network can inject malicious configuration Correct answer.
  4. Slower boot times

Explanation

Without signature verification, anyone able to reach the update endpoint can push configuration that changes device behavior or redirects data. Power, radio range, and boot time are performance concerns unrelated to the integrity gap.