* The netstat -n command displays active TCP connections, but addresses and port numbers are expressed numerically and no attempt is made to determine names12. This option can be useful for checking the output in integer form, as well as for avoiding possible delays caused by name resolution12.
* The netstat command without any parameters displays active TCP connections, but addresses and port numbers are resolved to their corresponding names, such as hostnames and service names12. This option can be less informative and more time-consuming than the -n option12.
* The netstat -a command displays all active TCP connections and the TCP and UDP ports on which the computer is listening12. This option can be useful for checking the availability and status of ports, but it does not show the output in integer form12.
* The netstat -e command displays Ethernet statistics, such as the number of bytes and packets sent and received12. This option can be useful for checking the network performance and utilization, but it does not show the network connections or their addresses and port numbers12.
References:
* 1: CompTIA Network+ N10-008 Study Guide, Chapter 5: Network Tools and Troubleshooting
* 2: netstat | Microsoft Learn
* : 28 Netstat Commands {A Comprehensive List With Examples} - phoenixNAP
* : How to Use the Netstat Command - Lifewire

EIGRP is an advanced distance vector routing protocol that is able to automatically update routing tables and also uses features of link-state routing protocols, such as the ability to send updates about the current topology of the network. EIGRP also has the ability to use a variety of algorithms to determine the best route for a packet to take, allowing for more efficient routing across the network.

The issue is that new employees are not able to print to the main networked copiers from their workstations after Switch 3 was added to the stack. Looking at the port configurations for Switch 3, we can see that the ports for printers (Ports 13-24) are shut down.
A . Enable the printer ports on Switch 3: This should be done because, as per the configuration shown in the image, these ports are currently shut down. Enabling them would restore connectivity for printing.
E . Reconfigure the VLAN on the printer ports on Switch 3: The VLAN for printers is set to 80 on Switch 3 while it is set to 60 on Switches 1 and 2. Changing VLAN of printer ports on Switch 3 to match with other switches (VLAN60) will ensure that they are all in the same broadcast domain and can communicate effectively.
The duplex settings do not need reconfiguration as they are already set to full duplex across all switches which facilitates efficient two-way communication.
Reference:
CompTIA Network+ N10-008 Certification Study Guide, Chapter 3: Network Devices, page 115-116 CompTIA Network+ Certification Exam Objectives, Domain 2: Network Implementations, Objective 2.1: Given a scenario, install and configure the appropriate networking devices, Sub-objective: Configure switch ports Ace Your CompTIA Network+ Exam: Explore Top Study Resources, Section: CompTIA Network+ Certification Kit: Exam N10-008 6th Edition

An incorrect subnet mask on the serial interface would prevent proper communication between the router and the service provider, affecting internet access. The other options are less likely to be the cause: an incorrect Ethernet IP address would affect local network connectivity, an incorrect loopback address does not impact external network access, and an incorrect default gateway is not relevant for serial link configurations.