network guide to networks fourth edition l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Network+ Guide to Networks, Fourth Edition PowerPoint Presentation
Download Presentation
Network+ Guide to Networks, Fourth Edition

Loading in 2 Seconds...

play fullscreen
1 / 30

Network+ Guide to Networks, Fourth Edition - PowerPoint PPT Presentation


  • 360 Views
  • Uploaded on

Network+ Guide to Networks, Fourth Edition. Chapter 13 Ensuring Integrity and Availability. What Are Integrity and Availability?. Integrity: soundness of network’s programs, data, services, devices, and connections

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Network+ Guide to Networks, Fourth Edition' - tobit


Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
network guide to networks fourth edition

Network+ Guide to Networks, Fourth Edition

Chapter 13

Ensuring Integrity and Availability

what are integrity and availability
What Are Integrity and Availability?
  • Integrity: soundness of network’s programs, data, services, devices, and connections
  • Availability: how consistently and reliably file or system can be accessed by authorized personnel
    • Need well-planned and well-configured network
    • Data backups, redundant devices, protection from malicious intruders
  • Phenomena compromising integrity and availability:
    • Security breaches, natural disasters, malicious intruders, power flaws, human error

Network+ Guide to Networks, 4e

viruses
Viruses
  • Program that replicates itself with intent to infect more computers
    • Through network connections or exchange of external storage devices
    • Typically copied to storage device without user’s knowledge
  • Trojan horse: program that disguises itself as something useful but actually harms system
    • Not considered a virus

Network+ Guide to Networks, 4e

types of viruses
Types of Viruses
  • Boot sector viruses:located in boot sector of computer’s hard disk
    • When computer boots up, virus runs in place of computer’s normal system files
    • Removal first requires rebooting from uninfected, write-protected disk with system files on it
  • Macro viruses:take form of macro that may be executed as user works with a program
    • Quick to emerge and spread
    • Symptoms vary widely

Network+ Guide to Networks, 4e

types of viruses continued
Types of Viruses (continued)
  • File-infected viruses: attach to executable files
    • When infected executable file runs, virus copies itself to memory
    • Can have devastating consequences
    • Symptoms may include damaged program files, inexplicable file size increases, changed icons for programs, strange messages, inability to run a program
  • Worms: programs that run independently and travel between computers and across networks
    • Not technically viruses
    • Can transport and hide viruses

Network+ Guide to Networks, 4e

types of viruses continued6
Types of Viruses (continued)
  • Trojan horse: program that claims to do something useful but instead harms system
  • Network viruses: propagated via network protocols, commands, messaging programs, and data links
  • Bots: program that runs automatically, without requiring a person to start or stop it
    • Many bots spread through Internet Relay Chat (IRC)
    • Used to damage/destroy data or system files, issue objectionable content, further propagate virus

Network+ Guide to Networks, 4e

virus characteristics
Virus Characteristics
  • Encryption: encrypted virus may thwart antivirus program’s attempts to detect it
  • Stealth: stealth viruses disguise themselves as legitimate programs or replace part of legitimate program’s code with destructive code
  • Polymorphism: polymorphic viruses change characteristics every time transferred
  • Time-dependence: time-dependent viruses programmed to activate on particular date

Network+ Guide to Networks, 4e

virus protection antivirus software
Virus Protection: Antivirus Software
  • Antivirus software should at least:
    • Detect viruses through signature scanning
    • Detect viruses through integrity checking
    • Detect viruses by monitoring unexpected file changes or virus-like behaviors
    • Receive regular updates and modifications from a centralized network console
    • Consistently report only valid viruses
      • Heuristic scanning techniques attempt to identify viruses by discovering “virus-like” behavior (may give “false positives”)

Network+ Guide to Networks, 4e

antivirus policies
Antivirus Policies
  • Provide rules for using antivirus software and policies for installing programs, sharing files, and using floppy disks
  • Suggestions for antivirus policy guidelines:
    • Every computer in organization equipped with virus detection and cleaning software
    • Users should not be allowed to alter or disable antivirus software
    • Users should know what to do in case virus detected

Network+ Guide to Networks, 4e

fault tolerance
Fault Tolerance
  • Capacity for system to continue performing despite unexpected hardware or software malfunction
  • Failure: deviation from specified level of system performance for given period of time
  • Fault: involves malfunction of system component
    • Can result in a failure
  • Varying degrees
    • At highest level, system remains unaffected by even most drastic problems

Network+ Guide to Networks, 4e

power power flaws
Power: Power Flaws
  • Power flaws that can damage equipment:
    • Surge: momentary increase in voltage due to lightning strikes, solar flares, or electrical problems
    • Noise: fluctuation in voltage levels caused by other devices on network or electromagnetic interference
    • Brownout: momentary decrease in voltage; also known as a sag
    • Blackout: complete power loss

Network+ Guide to Networks, 4e

upss uninterruptible power supplies
UPSs (Uninterruptible Power Supplies)
  • Battery-operated power source directly attached to one or more devices and to power supply
    • Prevents undesired features of outlet’s A/C power from harming device or interrupting services
    • Standby UPS: provides continuous voltage to device
      • Switch to battery when power loss detected
    • Online UPS: uses power from wall outlet to continuously charge battery, while providing power to network device through battery

Network+ Guide to Networks, 4e

servers
Servers
  • Make servers more fault-tolerant by supplying them with redundant components
    • NICs, processors, and hard disks
    • If one item fails, entire system won’t fail
    • Enable load balancing

Network+ Guide to Networks, 4e

server mirroring
Server Mirroring
  • Mirroring: one device or component duplicates activities of another
  • Server Mirroring: one server duplicates transactions and data storage of another
    • Must be identical machines using identical components
    • Requires high-speed link between servers
    • Requires synchronization software
    • Form of replication
  • Servers can stand side by side or be positioned in different locations

Network+ Guide to Networks, 4e

clustering
Clustering
  • Link multiple servers together to act as single server
    • Share processing duties
    • Appear as single server to users
    • If one server fails, others automatically take over data transaction and storage responsibilities
    • More cost-effective than mirroring
    • To detect failures, clustered servers regularly poll each other
    • Servers must be close together

Network+ Guide to Networks, 4e

storage raid redundant array of independent or inexpensive disks
Storage: RAID (Redundant Array of Independent (or Inexpensive) Disks)
  • Collection of disks that provide fault tolerance for shared data and applications
    • Disk array
    • Collection of disks that work together in RAID configuration, often referred to as RAID drive
      • Appear as single logical drive to system
  • Hardware RAID: set of disks and separate disk controller
    • Managed exclusively by RAID disk controller
  • Software RAID: relies on software to implement and control RAID techniques

Network+ Guide to Networks, 4e

raid level 0 disk striping
RAID Level 0―Disk Striping
  • Simple implementation of RAID
    • Not fault-tolerant
    • Improves performance

Figure 13-6: RAID Level 0—disk striping

Network+ Guide to Networks, 4e

raid level 1 disk mirroring
RAID Level 1—Disk Mirroring
  • Data from one disk copied to another disk automatically as information written
    • Dynamic backup
    • If one drive fails, disk array controller automatically switches to disk that was mirroring it
    • Requires two identical disks
    • Usually relies on system software to perform mirroring
  • Disk duplexing: similar to disk mirroring, but separate disk controller used for each disk

Network+ Guide to Networks, 4e

raid level 1 disk mirroring continued
RAID Level 1—Disk Mirroring (continued)

Figure 13-7: RAID Level 1—disk mirroring

Network+ Guide to Networks, 4e

raid level 5 disk striping with distributed parity
RAID Level 5—Disk Striping with Distributed Parity
  • Data written in small blocks across several disks
    • Parity error checking information distributed among disks
    • Highly fault-tolerant
    • Very popular
    • Failed disk can be replaced with little interruption
  • Hot spare: disk or partition that is part of array, but used only in case a RAID disks fails
  • Cold spare: duplicate component that can be installed in case of failure

Network+ Guide to Networks, 4e

raid level 5 disk striping with distributed parity continued
RAID Level 5—Disk Striping with Distributed Parity (continued)

Figure 13-9: RAID Level 5—disk striping with distributed parity

Network+ Guide to Networks, 4e

nas network attached storage
NAS (Network Attached Storage)
  • Specialized storage device that provides centralized fault-tolerant data storage
    • Maintains own interface to LAN
    • Contains own file system optimized for saving and serving files
    • Easily expanded without interrupting service
    • Cannot communicate directly with network clients

Network+ Guide to Networks, 4e

nas continued
NAS (continued)

Figure 13-10: Network attached storage on a LAN

Network+ Guide to Networks, 4e

sans storage area networks
SANs (Storage Area Networks)

Figure 13-11: A storage area network

Network+ Guide to Networks, 4e

data backup
Data Backup
  • Copy of data or program files created for archiving or safekeeping
    • No matter how reliable and fault-tolerant you believe your server’s hard disk (or disks) to be, still risk losing everything unless you make backups on separate media and store them off-site
  • Many options exist for making backups

Network+ Guide to Networks, 4e

optical media
Optical Media
  • Capable of storing digitized data
    • Uses laser to write and read data
    • CD-ROMs and DVDs
  • Requires proper disk drive to write data
  • Writing data usually takes longer than saving data to another type of media

Network+ Guide to Networks, 4e

external disk drives
External Disk Drives
  • Storage devices that can be attached temporarily to a computer via USB, PCMCIA, FireWire, or Compact-Flash port
    • Removable disk drives
  • For backing up large amounts of data, likely to use external disk drive with backup control features, high capacity, and fast read-write access
  • Faster data transfer rates than optical media or tape backups

Network+ Guide to Networks, 4e

backup strategy continued
Backup Strategy (continued)
  • Archive bit: file attribute that can be checked or unchecked
    • Indicates whether file must be archived
  • Backup methods use archive bit in different ways
    • Full backup: all data copied to storage media, regardless of whether data is new or changed
      • Archive bits set to “off” for all files
    • Incremental backup: copies only data that has changed since last full or incremental backup
      • Unchecks archive bit for every file saved
    • Differential backup:does not uncheck archive bits for files backed up

Network+ Guide to Networks, 4e

disaster recovery disaster recovery planning
Disaster Recovery: Disaster Recovery Planning
  • Disaster recovery: process of restoring critical functionality and data after enterprise-wide outage
  • Disaster recovery plan accounts for worst-case scenarios
    • Contact names and info for emergency coordinators
    • Details on data and servers being backed up, backup frequency, backup location, how to recover
    • Details on network topology, redundancy, and agreements with national service carriers
    • Strategies for testing disaster recovery plan
    • Plan for managing the crisis

Network+ Guide to Networks, 4e

disaster recovery contingencies
Disaster Recovery Contingencies
  • Several options for recovering from disaster
    • Cold site: place where computers, devices, and connectivity necessary to rebuild network exist
      • Not configured, updated, or connected
    • Warm site: same as cold site, but some computers and devices appropriately configured, updated, or connected
    • Hot site: computers, devices, and connectivity necessary to rebuild network are appropriately configured, updated, and connected to match network’s current state

Network+ Guide to Networks, 4e