If cadets are using company phone numbers to make unsolicited calls, and the logs confirm the numbers are not being spoofed, it suggests that the SIP (Session Initiation Protocol) server's security settings might be weak. This could allow unauthorized access or exploitation of the company's telephony services, potentially leading to misuse by unauthorized individuals.
References = CompTIA Security+ SY0-701 study materials, especially on SIP security and common vulnerabilities.

Jailbreaking is the process of removing restrictions imposed by the manufacturer on a smartphone, allowing the user to install unauthorized software and features not available through official app stores. This action typically voids the warranty and can introduce security risks by bypassing built-in protections.
* SOU (Statement of Understanding) is not related to modifying devices.
* Cross-site scripting is a web-based attack technique, unrelated to smartphone software.
* Side loading refers to installing apps from unofficial sources but without necessarily removing built-in restrictions like jailbreaking does.

An application allow list is a security technique that specifies which applications are permitted to run on a system or a network. An application allow list can block unknown programs from executing by only allowing the execution of programs that are explicitly authorized and verified. An application allow list can prevent malware, unauthorized software, or unwanted applications from running and compromising the security of the system or the network12.
The other options are not the best ways to block unknown programs from executing:
Access control list: This is a security technique that specifies which users or groups are granted or denied access to a resource or an object. An access control list can control thepermissions and privileges of users or groups, but it does not directly block unknown programs from executing13.
Host-based firewall: This is a security device that monitors and filters the incoming and outgoing network traffic on a single host or system. A host-based firewall can block or allow network connections based on predefined rules, but it does not directly block unknown programs from executing1 .
DLP solution: This is a security system that detects and prevents the unauthorized transmission or leakage of sensitive data. A DLP solution can protect the confidentiality and integrity of data, but it does not directly block unknown programs from executing1 .
References = 1: CompTIA Security+ SY0-701 Certification Study Guide, page 972: Application Whitelisting
- CompTIA Security+ SY0-701 - 3.5, video by Professor Messer3: CompTIA Security+ SY0-701 Certification Study Guide, page 98. : CompTIA Security+ SY0-701 Certification Study Guide, page 99. :
CompTIA Security+ SY0-701 Certification Study Guide, page 100.

The best answer is B. Updating default credentials and applying network segmentation.
IoT devices often present increased security risk because they may have weak default settings, limited security features, and persistent network connectivity. Two of the most effective ways to reduce this risk are:
Updating default credentialsMany IoT devices come with default usernames and passwords that are widely known or easy to guess. Leaving default credentials unchanged creates a major security weakness.
Applying network segmentationSegmenting IoT devices onto a separate network or VLAN limits their ability to interact with critical corporate systems. If one device is compromised, segmentation helps contain the threat and reduces lateral movement.
Why the other options are incorrect:
A). Assigning static IP addresses to the devicesStatic IP addresses may help with management and inventory, but they do not significantly reduce the core security risk.
C). Connecting the devices to the guest Wi-Fi to prevent interactions with corporate ITThis may seem helpful, but guest Wi-Fi is typically designed for temporary user access, not secured management of business IoT systems. It is not the best practice compared with a properly segmented and controlled IoT network.
D). Allowing the vendor to have remote access for day-to-day managementRoutine vendor remote access can increase risk if not tightly controlled. Third-party access should be limited, monitored, and secured, not broadly allowed as a default control.
From the SY0-701 perspective, IoT security commonly emphasizes changing insecure defaults, restricting access, segmentation, and reducing exposure. Therefore, B is the strongest and most complete answer.