Here you will find a list of terms that might interest you or explain things a little better.

VPN:  A virtual private network (VPN) is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires. The link-layer protocols of the virtual network are said to be tunneled through the larger network when this is the case. One common application is secure communications through the public Internet, but a VPN need not have explicit security features, such as authentication or content encryption.

SCO CSA:  (Certified systems administrator), The SCO Certified System Administrator (CSA) certification is the basic level of certification for SCO UNIX products, and is the first step in achieving your ACE or Master ACE advance certifications. The CSA exam tests knowledge gained by completing either the UnixWare or OpenServer System Administration I and II courses. After taking these courses, a candidate for the SCO CSA should be able to install the system, do user and group management, be familiar with the SCO Admin tool, install and configure print services, and perform other general system management tasks. With your CSA, employers and clients will know that you posses the needed skills to efficiently administer SCO UNIX products.

SCO ACE: (advanced certified engineer), The Advanced Certified Engineer (ACE) certification builds on the foundation of the CSA certification and expands the engineer's credentials to network administration and shell programming. Candidates for the ACE certification should have taken the Network Administration course for their respective product track and the Shell Programming for System Administrators course (the shell programming class covers both UnixWare and OpenServer). Upon completion of the courses above, the candidate must take and pass the exam associated with each course to achieve their ACE certification. The ACE certification represents a superior level of expertise with SCO UNIX products.

SCO Master ACE: (advanced certified engineer) , The SCO ACE certification is a significant achievement, and represents a high level of expertise in the SCO UNIX track you pursued (either UnixWare or OpenServer). However, you may find that your employer or customers require the same level of expertise in the SCO UNIX operating system you did not get your ACE for. The SCO Master ACE recognizes those UNIX professionals who have demonstrated ACE level of expertise in more one ACE track. For example, if you achieved your ACE certification in the OpenServer track, you could follow the ACE track for UnixWare and obtain your Master ACE level of certification. Those who achieve their Master ACE certification differentiate themselves from other UNIX professionals by the breadth and scope of their expertise.

HA systems: High availability is a system design protocol and associated implementation that ensures a certain absolute degree of operational continuity during a given measurement period. Availability refers to the ability of the user community to access the system, whether to submit new work, update or alter existing work, or collect the results of previous work. If a user cannot access the system, it is said to be unavailable. Generally, the term downtime is used to refer to periods when a system is unavailable.

DR:  Disaster recovery is the process, policies and procedures of restoring operations critical to the resumption of business, including regaining access to data (records, hardware, software, etc.), communications (incoming, outgoing, toll-free, fax, etc.), workspace, and other business processes after a natural or human-induced disaster.

DRP: Disaster Recovery Plan. To increase the opportunity for a successful recovery of valuable records, a well-established and thoroughly tested disaster recovery plan must be developed.  A disaster recovery plan (DRP) should also include plans for coping with the unexpected or sudden loss of communications and/or key personnel,  the focus of which is data protection.

MTA: Message/mail transfer agent. the program responsible for receiving incoming e-mails and delivering the messages to individual users. The MTA transfers messages between computers. Hidden from the average user, it is responsible for routing messages to their proper destinations.

Postfix: Postfix is an Open source email server for Unix and linux. It is an mta that was started as an alternative to the widely-used Sendmail program. It is the same MTA used by smtp.saix.net as is considered one of the faster mail servers around.

Sendmail:  On the Internet, sendmail is the oldest and most popular Unix-based implementation of the Simple Mail Transfer Protocol (SMTP) for transmitting e-mail. It has started showing its age by not having more features added and being unable to do what the newer mta's can.