Integrity is the security concept that is related to ensuring that encrypted data is not edited while in transit. Integrity is one of the three main goals of information security, along with confidentiality and availability. Integrity means that data is protected from unauthorized modification or corruption during storage, processing, or transmission. Integrity can be achieved by using various techniques, such as hashing, digital signatures, checksums, or message authentication codes (MACs). These techniques can verify the authenticity and validity of the data by detecting any changes or tampering that may have occurred. Reference: [CompTIA Network+ Certification Exam Objectives], What Is Data Integrity? | Definition & Examples | Forcepoint

The appropriate next step in this situation would be to check for the existence of a known exploit in order to assess the risk. This is important because it will help the network administrator determine the severity of the vulnerability and the potential impact it could have on the organization. Once the network administrator has assessed the risk, they can then take appropriate action to address the vulnerability. This might include patching the application, deploying a new server to host the application, or implementing other security measures to mitigate the risk. It is generally not advisable to immediately shut down the vulnerable application server, as this could disrupt business operations and cause significant downtime. Similarly, installing a network access control agent on the server may not be the most effective solution, as it would not address the underlying vulnerability.

To detect the exact break point of a fiber link, an engineer should use an OTDR (Optical Time Domain Reflectometer). This device sends a series of pulses into the fiber, measuring the time it takes for the pulses to reflect back, and can pinpoint the exact location of the break.
Reference:
Network+ N10-007 Certification Exam Objectives, Objective 2.5: Given a scenario, troubleshoot copper cable issues.
FS: OTDR (Optical Time Domain Reflectometer) Testing Principle and Applications

Audit logs are records of the actions performed by users or processes on a system or network device. They can provide information about who made what changes, when, and why. Audit logs are essential for detecting and investigating security incidents, as well as for ensuring compliance with policies and regulations. Audit logs can help the network security engineer to identify the source of the unauthorized configuration changes to the boundary firewall, as well as the scope and impact of the changes.
Reference
1 - Changes to Cyber Essentials requirements - April 2021 update
2 - 8 Firewall Best Practices for Securing the Network
3 - How to secure your network boundaries with a firewall

A VLAN (virtual local area network) is a logical grouping of devices that share the same broadcast domain, regardless of their physical location or connection.
VLANs can be used to separate different types of traffic on a network, such as data, voice, video, etc.
VLANs can also improve network performance, security, and management by reducing the size of broadcast domains and limiting unnecessary traffic.
To pass both data and telephony on an access port, the network engineer needs to configure the port as a trunk port, which can carry multiple VLANs using tags.
The network engineer also needs to assign the data and voice devices to different VLANs, and enable quality of service (QoS) to prioritize the voice traffic over the data traffic.
VoIP (voice over IP) is a technology that allows voice communication over an IP network, such as the Internet. VoIP is not a feature that can be configured on an access port, but rather a type of traffic that can be carried by a VLAN.
VIP (virtual IP) is an IP address that is shared by multiple devices or servers, usually for load balancing or redundancy purposes. VIP is not a feature that can be configured on an access port, but rather a type of address that can be assigned to a device or server.
VRRP (virtual router redundancy protocol) is a protocol that allows multiple routers to form a virtual router group and provide backup for each other in case of failure. VRRP is not a feature that can be configured on an access port, but rather a protocol that can be implemented on a router.
Reference:
CompTIA Network+ N10-008 Study Guide, Chapter 3: Deploying Ethernet Switching, Section 3.2: VLANs and Trunking, pp. 111-1201 Professor Messer's CompTIA N10-008 Network+ Course Notes, Section 3.2: VLANs and Trunking, pp. 28-292 Professor Messer's CompTIA N10-008 Network+ Training Course, Video 3.2: VLANs and Trunking3