10GBASE-LR is the best choice for connecting two data centers that are 6.2 miles (10 km) apart via fiber, because it supports a maximum distance of 6.2 miles (10 km) over single-mode fiber. 10GBASE-SR and
1000BASE-SX are designed for short-range connections over multi-mode fiber, and they can only reach up to
1,312 feet (400 m) and 1,804 feet (550 m), respectively. 10000BASE-LX is a typo and does not exist as a standard.
References:
* Network Transceivers - CompTIA Network+ N10-007 - 2.11
* CompTIA Network+ Certification Exam Objectives2

To locate a device's network port on a switch, a technician should review the switch's MAC address table. The MAC address table maintains a list of MAC addresses of devices connected to each port on the switch. By checking the MAC address of the device in question, the technician can identify the port to which the device is connected.

Explanation
Network Function Virtualization (NFV) is a technology that allows for the virtualization of a replica of a network's physical topology and the way it behaves without changing the logical topology and the way that devices are managed. NFV allows for the virtualization of network functions such as routers, firewalls, and switches, resulting in increased flexibility and scalability. This makes NFV an ideal technology for companies looking to virtualize a replica of their internal physical network.

The network statistics ( netstat ) command is a networking tool used for troubleshooting and configuration, that can also serve as a monitoring tool for connections over the network. Both incoming and outgoing connections, routing tables, port listening, and usage statistics are common uses for this command.

An A record, also known as an address record, is a type of DNS record that maps a hostname to an IPv4 address. An A record is used to resolve a domain name to an IP address, so that clients can connect to the server or service by using the domain name instead of the IP address. For example, an A record can map www.example.com to 192.0.2.1.
An A record is the most common type of DNS record for cloud DNS, as it allows the company to use a custom domain name for their cloud services, such as web hosting, email, or storage. An A record can also be used to create subdomains, such as blog.example.com or mail.example.com, that point to different IP addresses or servers.
The other options are not correct because they are not the best type of DNS record for cloud DNS. They are:
MX. MX stands for mail exchange, and it is a type of DNS record that specifies the mail servers that are responsible for receiving and delivering email messages for a domain name. MX records are used for email services, but they are not sufficient for cloud DNS, as they do not map a hostname to an IP address.
CNAME. CNAME stands for canonical name, and it is a type of DNS record that specifies an alias name for another domain name. CNAME records are used to create multiple names for the same IP address or server, such as www.example.com and example.com. CNAME records are useful for cloud DNS, but they are not the best type, as they depend on another A record to resolve the IP address.
NS. NS stands for name server, and it is a type of DNS record that delegates a DNS zone to an authoritative server. NS records are used to specify which DNS servers are responsible for answering queries for a domain name or a subdomain. NS records are essential for cloud DNS, but they are not the best type, as they do not map a hostname to an IP address.
Reference 1: DNS records overview | Google Cloud 2: Network+ (Plus) Certification | CompTIA IT Certifications 3: ClouDNS: What is a DNS record?