Comprehensive and Detailed Explanation:
When anew VLAN is created, it typically exists on a different subnet. IfDHCP servers are on a different VLAN, the networkneeds an IP helper addressto forward DHCP requests correctly. Without it, clients in the new VLANwon't receive an IP address.
Breakdown of Options:
* A. Scope size- Increasing the DHCP scope would not resolve the issue if requestsaren't reaching the server.
* B. Address reservations- Reservations only assign specific addresses to devices; they do not fix DHCP communication issues.
* C. Lease time- Changing the lease timedoes not impact DHCP functionality across VLANs.
* D. IP helper-Correct answer.This forwardsDHCP requestsacross VLANs to the DHCP server.

Comprehensive and Detailed Explanation:
Thenetstatoutput shows thatmultiple ports are open, includingTelnet (23), FTP (20), and TFTP (69), which are potential security risks.Disabling unused portsminimizes the attack surface, reducing security vulnerabilities.
Breakdown of Options:
* A. Disable the unused ports-Correct answer.Unused portsshould be closedto prevent unauthorized access.
* B. Enforce access control lists- ACLs help control access but donot disable unnecessary services.
* C. Perform content filtering- Content filtering controlsweb traffic,not port security.
* D. Set up a screened subnet- ADMZ (screened subnet)improves security but doesnot address open ports.

The most probable issue is with thetransceiver model. Not all transceivers are compatible with multimode fiber, and the specific type (e.g., SFP, SFP+) and its wavelength must match the fiber cable type. If a port works on one switch but not the other with the same cable, this is a strong indicator of incompatible or faulty transceiver hardware.
Reference:

The netstat output shows that multiple ports are open, including Telnet (23), FTP (20), and TFTP (69), which are potential security risks. Disabling unused ports minimizes the attack surface, reducing security vulnerabilities.
Breakdown of Options:
A). Disable the unused ports - Correct answer. Unused ports should be closed to prevent unauthorized access.
B). Enforce access control lists - ACLs help control access but do not disable unnecessary services.
C). Perform content filtering - Content filtering controls web traffic, not port security.
D). Set up a screened subnet - A DMZ (screened subnet) improves security but does not address open ports.
Reference:
CompTIA Network+ (N10-009) Official Study Guide - Domain 3.4: Given a scenario, implement network security measures.
CIS Benchmark for Linux & Windows Server Hardening

Introduction to Security Zones:
Security zones are logical segments within a network designed to enforce security policies and control access. They help in segregating and securing different parts of the network.
Types of Security Zones:
Trusted Zone: This is the most secure zone, typically used for internal corporate networks where only trusted users have access.
Extranet: This zone allows controlled access to external partners, vendors, or customers.
VPN (Virtual Private Network): While VPNs are used to create secure connections over the internet, they are not a security zone themselves.
Public Zone: This zone is the least secure and is typically used for public-facing services accessible by anyone.
Trusted Zone Implementation:
The trusted zone is configured to include internal corporate users and resources. Access controls, firewalls, and other security measures ensure that only authorized personnel can access this zone.
Internal network segments, such as the finance department, HR, and other critical functions, are usually placed in the trusted zone.
Example Configuration:
Firewall Rules: Set up rules to allow traffic only from internal IP addresses.
Access Control Lists (ACLs): Implement ACLs on routers and switches to restrict access based on IP addresses and other criteria.
Segmentation: Use VLANs and subnetting to segment and isolate the trusted zone from other zones.
Explanation of the Options:
A . Extranet: Suitable for external partners, not for internal-only access.
B . Trusted: The correct answer, as it provides controlled access to internal corporate users.
C . VPN: A method for secure remote access, not a security zone itself.
D . Public: Suitable for public access, not for internal corporate users.
Conclusion:
Implementing a trusted zone is the best solution for controlling access within a corporate network. It ensures that only trusted internal users can access sensitive resources, enhancing network security.
Reference:
CompTIA Network+ guide detailing security zones and their implementation in a corporate network (see page Ref 9fBasic Configuration Commands).