The Domain Name System (DNS) is responsible for translating domain names into IP addresses. By blocking malicious sites from resolving correctly, the DNS server is able to prevent the user from accessing those sites. Therefore, the DNS server setting on the user's router needs to be changed to enable this functionality12
3.

The technician should check the level of network utilization to determine if there is an excessive amount of traffic that may be causing the slow access to the network fileshare. This can be done using network monitoring tools to track the amount of data being transmitted on the network. References: CompTIA A+ Certification Exam Objectives 1001, 2.9

Installing an M.2 SSD will improve a workstation's overall response time for frequently used applications and data without removing the current hard drive. M.2 drives are faster and more efficient than traditional hard drives, making them a good option for increasing overall performance. References: CompTIA A+ Certification Exam Core 1 Exam Objectives - 1.5 Given a scenario, configure storage devices and use appropriate media

The best component for a technician to upgrade to fix the issue of slow performance writing data is B. HDD.
HDD stands for hard disk drive, which is a type of storage device that uses physical disks to store data. HDDs have moving parts that can slow down the read and write operations, especially when the data is fragmented or the disk is full12.
A better alternative to HDDs is SSDs, which stands for solid state drives. SSDs use flash memory and do not have any moving parts. SSDs can read and write data faster and use less power, which can improve the performance and battery life of the laptop13. Upgrading to an SSD can provide a significant improvement in performance2.
The other components are not as relevant or effective as upgrading the HDD. RAM stands for random access memory, which is a type of memory that stores temporary data for the CPU to process. RAM can affect the overall speed of the laptop, but it does not directly affect the writing performance of the storage device1. TPM stands for trusted platform module, which is a security chip that encrypts and protects data on the laptop. TPM does not affect the performance of the laptop, but rather its security1. CPU stands for central processing unit, which is the main processor of the laptop that executes instructions and calculations. CPU can affect the performance of the laptop, but it is not as easy or cost-effective to upgrade as the HDD1.