IT Operations - Computer Networks and Data Communication Flashcards
Computer network consists of two or more computing deices connected by a communications channel to exchange data
Common uses and applications of networks
A) file services
B) email services
C) Print services
D) Remot access capabilities
E) Directory services (identifies available on a network)
F) Network management
G) Internet connection services including
1) Dynamic host onciguration protocol (DHCP) - protocol used to obtain and release IP addresses; protocol enables computers to connote to an IP based network like internet
2)Domain name system (DNS) - system that translates network notes into IP addresses
Components of a network
Nodes - any device connected to network = node
1) client - a node, usually microcomputer, used by end users
2) server - node dedicated to providing devices or resources to the rest of network (a file server maintains centralized application and data files, print server provide access to HQ printers) servers indirectly used by end user
Transmission media - communication between nodes on network; link may be one of several types of wired or wireless media; LAN, WAN
Wide area networks (WANs) use public or shared communications lines
Wired communications media
A) copper or twisted pair
i. Traditionally used for phone connections
ii. The slowest, least secure (e.g. easy to tap) and most subject to interference of the wired media
iii. Recent modifications have, however, improved performance significantly
iv. Least expensive media
v. Performance degrades with cable length
b.
Coaxial cable – Similar to the cable used for television, coaxial cable is faster, more secure, and less subject to interference than twisted pair but has a slightly higher cost.
c.
Fiber optic cable – Extremely fast and secure, fiber optic cable communications are based on light pulses instead of electrical impulses; therefore they are not subject to electrical interference and the signal does not degrade over long distances; more expensive to purchase and to install.
Wireless communications media
A) microwave transmission - may use combo of terrestrial microwave and /or satellite microwave transmission (wan use)
B) WiFi or spread spectrum
I) used in both large and small networks
Ii) found in both lans and wans
Iii) generally slow than wired using coaxial or fiber optic
C) bluetooth - same radio frequencies as wifi but lower power consumption resulting in weaker connection
D) digital cellular (CDPD) - transmission of data over cellphone network used by WANS
Network operating system
Controls communication over network and access to network resources
1) peer to peer - all nodes share in communication to management; no central controller required (simple and inexpensive used by LANs)
2) client/server - server presides as mediator of communication on network and grants access to network resources; used by LANs and by world’s largest client - internet
3) Hierarchial operating systems -
A) use centralized point generally referred to as host computer
B) host manages communications and access but also performs most of data processing
C) nodes connected to these systems function as dumb terminals which are able to send and receive info but do no processing
D) used by WANs
Communications Devices
Link networks to other networks and to remote access - modems, hubs, repeaters, routers, gateways.
TYPES OF NETWORKS
Networks characterize by way constructed and managed and b network’s geographic reach
A) LAN - named because they were originally confined to very limited geographic areas. With inexpensive fiber optic cable, LAN can extend for many miles
B) Wide area networks WANS - National or international in scope
C) Storag area networks (SANs) - type of vatiatopn on Lans that connect storage devices to servers
D) Personal area networks PANs - home network that links devices used by an individual or family to one another an to internet
Network Mangement Tools
A.
Response Time Reports – How fast is the system responding to user commands? Generated reports should indicate average, best, and worst time responses across the system (e.g., by lines or systems).
B.
Downtime reports – Which portions of the system were unavailable and for how long?
C.
Online monitors – These monitors check transmission accuracy and errors.
D.
Network monitors – These monitors display network node status and availability.
E.
Protocol analyzers – Diagnostic tools that monitor packet flows across the system. They are useful in diagnosing the volume and nature of network traffic, and in analyzing network performance.
F.
Simple Network Management Protocol (SNMP) – A software-based, TCP/IP protocol that monitors network performance and security.
G.
Help desk reports – Useful in identifying network problems raised by users.
