A cellular card is a device that allows a laptop to connect to the internet using a cellular network, such as 4G or 5G. A cellular card can provide internet access when the user travels and does not have access to a Wi-Fi network. A cellular card may require a subscription plan from a cellular service provider. A Wi-Fi extender is a device that boosts the signal of an existing Wi-Fi network, but it does not provide internet access by itself.
Bluetooth is a wireless technology that allows devices to communicate over short distances, but it does not provide internet access either. GPS is a satellite-based system that provides location and navigation information, but it does not provide internet access as well. References: https://www.comptia.org/blog/what-is- a-cellular-card

A media converter is a network device that operates as a bridge function, which means it connects two different types of network media, such as copper and fiber optic cables, and converts signals between them.
This allows network devices that use different media types to communicate with each other over long distances or in different environments, without requiring major changes or upgrades to the existing network infrastructure. Reference: https://www.comptia.org/training/books/a-core-1-220-1101-study-guide (page 73)

Once the technician has determined that the power supply is likely to be defective, they should establish a plan of action to resolve the problem. This may include replacing the power supply or further testing to confirm that it is indeed defective. After establishing a plan of action, the technician should implement the solution and verify that it has resolved the issue.

Shared resources is the concept that allows several websites from different companies to be housed on the same virtual server. A virtual server is a software-based server that runs on a physical server and can host multiple virtual machines (VMs). Each VM can run a different operating system and application, such as a website, and have its own allocated resources, such as CPU, memory, disk space, and network bandwidth.
However, the VMs share the underlying hardware resources of the physical server, which reduces the cost and complexity of maintaining separate servers for each website. This also enables rapid scalability, as new VMs can be created or deleted as needed.
One of the methods to host multiple websites on the same virtual server is to use virtual hosts. Virtual hosts are a feature of web servers, such as Apache, that allow the web server to serve different websites based on the domain name or IP address requested by the client. For example, a web server can host two websites, a.
example.com and b.example.com, on the same virtual server and the same port (such as 80 or 443), by using virtual hosts to map each domain name to a different document root directory. The web server will then deliver the content of the corresponding website to the client based on the domain name in the HTTP request header.
References:
* How to Host Multiple Websites With One Apache Server1
* How to run multiple sites on one apache instance2
* Multiple different website hosting on same port 443 and same server or ...3
* When several name-based virtual hosts on the same web server share the ...4
* How to Host Multiple Sites on One Server - Server Mania5

Port 21 is used by FTP (File Transfer Protocol) for file transfers. Port 53 is for DNS, port 68 is for DHCP, and port 389 is for LDAP. Understanding standard network ports is essential in CompTIA A+ Core 1 objectives, especially in networking and troubleshooting scenarios.