Page 1293 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

could be severed? If there are no alternative fiber ingress points, can
you supplement a fiber connection with wireless connectivity? Do your

alternate processing sites have sufficient network capacity to carry the
full burden of operations in the event of a disaster?

If you quickly answered “no” to the question whether you

have critical business systems that rely on water, sewers, natural
gas, or other utilities, think again. Do you consider people a critical
business system? If a major storm knocks out the water supply to
your facilities and you need to keep those facilities up and running,
can you supply your employees with enough drinking water to

meet their needs?

What about your fire protection systems? If any of them are water
based, is there a holding tank system in place that contains ample
water to extinguish a serious building fire if the public water
system is unavailable? Fires often cause serious damage in areas
ravaged by storms, earthquakes, and other disasters that might
also interrupt the delivery of water.

Hardware/Software Failures

Like it or not, computer systems fail. Hardware components simply
wear out and refuse to continue performing, or they suffer physical

damage. Software systems contain bugs or fall prey to improper or
unexpected inputs. For this reason, BCP/DRP teams must provide
adequate redundancy in their systems. If zero downtime is a
mandatory requirement, the best solution is to use fully redundant
failover servers in separate locations attached to separate
communications links and infrastructures (also designed to operate in

a failover mode). If one server is damaged or destroyed, the other will
instantly take over the processing load. For more information on this
concept, see the section “Remote Mirroring” later in this chapter.

Because of financial constraints, it isn’t always feasible to maintain
fully redundant systems. In those circumstances, the BCP/DRP team
should address how replacement parts can be quickly obtained and