Windows Server is a brand name for a group of server operating systems released by Microsoft. wikipedia.org

Microsoft Exchange Server is the server side of a client_server, collaborative application product developed by Microsoft. It is part of the Microsoft Servers line of server products and is used by enterprises using Microsoft infrastructure products. wikipedia.org

Active Directory (AD) is a directory service created by Microsoft for Windows domain networks. wikipedia.org

A firewall is a device or set of devices designed to permit or deny network transmissions based upon a set of rules and is frequently used to protect networks from unauthorized access while permitting legitimate communications to pass. wikipedia.org

A network administrator, network analyst or network engineer is a person responsible for the maintenance of computer hardware and software that comprises a computer network. This normally includes deploying, configuring, maintaining and monitoring active network equipment. wikipedia.org

Zimbra Collaboration Suite (ZCS) is a groupware email server and web client created by Zimbra, Inc., located in Palo Alto, California, USA. wikipedia.org

VMware ESX is an enterprise-level computer virtualization product offered by VMware, Inc. ESX is a component of VMware's larger offering, VMware Infrastructure, and adds management and reliability services to the core server product. wikipedia.org

Network security consists of the provisions and policies adopted by the network administrator to prevent and monitor unauthorized access, misuse, modification, or denial of the computer network and network-accessible resources. wikipedia.org

VMware, Inc. is an American software company that provides cloud and virtualization software and services. wikipedia.org

pfSense is an open source firewall/router distribution based on FreeBSD. pfSense is meant to be installed on a personal computer and is noted for its reliability and offering features often only found in expensive commercial firewalls. wikipedia.org

Cisco Certified Network Associate (CCNA) Routing and Switching is a certification program for entry-level network engineers that helps maximize your investment in foundational networking knowledge.

Cisco Systems, Inc. is an American multinational corporation that designs, manufactures, and sells networking equipment. It has a full range of router products from small business to enterprise solutions, typically using its own Cisco IOS operating system. wikipedia.org