Chapter 9 Resilience and Physical Security

Question 1

Redundancy

Answer 1

Having more than one of a system, service, device or component.

Question 2

Redundancy Design Elements

Answer 2

• Geographic dispersal of systems ensures that a single disaster, attack, or failure cannot destroy a system. Place data centers 90+ miles apart.
• Separation of servers used to avoid single rack being a point of failure.
• use of multiple network paths (multi-path) solutions
  -protection of power
• Power: UPS (uninterruptible power supply) for short term, generators for long term
  Diversity of Technologies (resilient, but costly)

Question 3

Load Balancer

Answer 3

Device that acts as a reverse proxy and distributes network or application traffic across multiple servers. This increases reliability and capacity of systems.

Question 4

NIC Teaming

Answer 4

Combines multiple network cards into a single virtual network connection. this balances loads and increases fault tolerance.

Question 5

RAID (redundant array of inexpensive disks)

Answer 5

Data Striping - spread across disks
Data Mirroring - completely copied
Parity - ensures data is not corrupted or lost
RAID 10 is best when speed and resilience are important and cost is not. RAID 5 and 6 can survive a drive loss but have slow performance.
ADD NOTES

Question 6

Backup Types:
Full
Incremental
Differential

Answer 6

Full backup copies the entire system or device.
Incremental backup copies everything since the last incremental backup.
Differential backup copies everything since the last full back up.

Question 7

Snapshot vs. Images

Answer 7

Snapshots capture full state of a system at the time the backup is completed. Common for VMs.

Images are similar, but are a complete copy of a system or server down to the bit level for the drive. Completely match the system, backup method of choice for servers.

Question 8

Backup storage types:
Tape
Disks
Optical Media
Flash Media

Answer 8

Tape is inexpensive
Disks are more expensive but faster than tape
Optical media like Blu-ray and DVD are not common bc capacity reason
Flash media fine for short term copies, not used at enterprise scale

Question 9

Online vs. Offline backup storage

Answer 9

Online is always available for fast retrieval and access, but require power and expense.
Offline is cheaper but slower to access. can be used to ensure an organization does not have a total data loss.

Question 10

Cloud Backups and software-defined infrastructure models

Answer 10

systems that would’ve once been backed up aren’t being backed up. Instead, the code that defines them is backed up as well as key data they are designed to access or provide.

Question 11

Considerations for cloud and offsite backup options

Answer 11

Bandwidth requirements, for backups themselves as well as restoration time.
Time to retrieve files and cost to retrieve files. (Amazon Glacier focuses on low cost storage but high cost retrieval, as well as slower times)
Reliability - some cloud backup providers have higher reliability than local tape or disk options.
New security models - separation of accounts, additional controls, etc.

Question 12

What is a SAN?

Answer 12

A Storage Area Network is a dedicated, high speed network that provides access to block level storage. CompTIA mentions SANs in two ways:

1. As a means of replicating data, where SANs use RAID to ensure that data is not lost.
2. SANs as a type of backup, in which they can be looked at as a network attached array of disks.

Question 13

What is NAS?

Answer 13

Network Attached Storage is a storage server connected to a computer network.

Question 14

What is nonpersistence?

Answer 14

The ability to have systems or services spun up or shut down as needed.

Question 15

What do you do when a system has been compromised or the OS is so seriously impacted that it can’t properly function?

Answer 15

Revert back to the last known good configuration. This can be done using live boot media, which is a bootable operating system that can be run from a thumb drive or DVD.

Question 16

Vertical vs. Horizontal Scalability

Scalability: spread load across many servers rather than requiring a larger single server.

Answer 16

Vertical Scalability requires a larger or more powerful system (can be expensive);
Horizontal scalability uses smaller systems but adds more of them, and allows for adjustment as needs grow or shrink.

Question 17

What are the three types of disaster recovery sites used for site resilience?

Answer 17

Hot Sites have all of the infrastructure and data needed to operate the organization.
Warm Sites have some or all of the systems needed but do not actually have the live data.
Cold Sites have space, power, and networking but are not prepared with systems or data, and are much cheaper to maintain.

Question 18

What is restoration order?

Answer 18

The order in which systems are restored after an outage.

One must balance the criticality of systems of the organization against the need for other infrastructure.

Question 19

Physical Site Security Concepts

Answer 19

Industrial Camouflage: unmarked or otherwise innocuous buildings
Fences
Lighting
Bollards are posts placed in front of entrances to prevent accidental or intentional vehicle accidents.
Drone defense
Badges required for entry. 
Alarm systems
Fire suppression systems.

Question 20

Secure Data Destruction

Answer 20

Most Secure document destruction:
- Burning
- Pulping
Less secure:
- shredding
Most secure device destruction:
- Pulverizing
less secure:
- Degaussing

Question 21

How should SSDs be wiped?
Zero wipe
Secure erase command
Full disk encryption with key destruction.

Answer 21

In order, Full disk encryption, then secure erase command if supported, then zero wiped.