CompTIA Network+ Chapter Three and Five
What does EMI do to data transmission?
Effects can range from an increase in error rate to a total loss of the data.
intermediate distribution frame (IDF)
A distribution frame in a central office or customer premises, which cross-connects the user cable media to individual user line circuits and may serve as a distribution point for multipair cables from the main distribution frame (MDF) or combined distribution frame (CDF) to individual cables connected to equipment in areas remote from these frames.
What are the significant difference between what hubs do and what switches do?
A switch recognizes frames. A switch ays attention to the source and destination MAC address of the incoming frame as well as the port on which it was received. A switch makes each of its ports a unique, singular collision domain.
zone file
A text file that describes a DNS zone. A DNS zone is a subset, often a single domain, of the hierarchical domain name structure of the DNS.
transparent bridging
A transparent bridge is essentially used to learn the MAC addresses of all nodes and their associated port, to filter incoming frames whose destination MAC addresses are located on the same incoming port, and to forward incoming frames to the destination MAC through their associated port@.
T1 Line
A type of data connection able to transmit a digital signal at 1.544 Mpbs.
megabit
A unit of data size or (when expressed per second) network speed, equal to one million or (strictly) 1,048,576 bits.
110 block
A wiring distribution point that has replaced most telephone wire installations and is also used for computer networking. On one side, wires are punched down; the other side has RJ-11 (for phone) or RJ-45 (for network) connections.
66 block
A wiring distribution point that uses the 25-pair cable and is a standard termination block containing 50 rows, which created an industry standard for easy termination of voice cabling. Used for old analog telephone connections.
AP
Access points. A hub that accepts wireless clients via an analog wireless signal. The wireless client modulates a digital signal to an analog signal, which the AP can read and demodulate back to a digital signal.
APIDS
Application protocol based intrusion detection system. Monitors traffic for a group of servers running the same application (such as SQL).
ASIC
Application-specific integrated circuit. An integrated circuit (IC) customized for a particular use, rather than intended for general-purpose use.
AAA
Authentication, authorization, and accounting is a term for a framework for intelligently controlling access to computer resources, enforcing policies, auditing usage, and providing the information necessary to bill for services.
Why are transmission speeds increasing?
Because the traffic demand is getting higher.
What are the two primary challenges caused by magnetic flux?
Because the wire is creating a current based on the 1s and 0s coursing through it, with the right tools, people can read the message in the wire without cutting it or removing the insulation. Wires can take on additional current if they're near any source of magnetism.
What are the two main types of proxy servers?
Caching proxy server. Web proxy server.
BNC coupler
Can be used to connect two male connectors together or two female connectors together.
firewall
Can employ them to filter packets based on rules that you or the network administrator create and configure to strictly delimit the type of information allowed to flow in and out of the network's Internet connection.
CNAME
Canonical name record. Commonly known as the alias record and allows hosts to have more than one name.
CSMA/ CD
Carrier sense multiple access with collision detection. Monitors for collisions. If one station sends a broadcast, all the others will receive it; yet based on the addressing found in the frame, only the intended recipient will actually listen and process it.
Radio Grade 58/RG-58
Coaxial cable often used for low-power signal and RF connections. The cable has a characteristic impedance of either 50 or 52 Ω.
How do you match the straight-through and crossover cables with the 568A and 568B standard?
568A + 568A = straight-through 568B + 568B = straight-through 568A + 568B = crossover
fiber optic coupler
A device used in optical fiber systems with one or more input fibers and one or several output fibers. Connect an ST to an SC connector, with loss of power (db).
CSU/DSU
A digital-interface device used to connect a data terminal equipment (DTE), such as a router, to a digital circuit, such as a Digital Signal 1 (T1) line.
IEEE
Institute of Electrical and Electronics Engineers.
What are the primary computer hardware environmental considerations?
Low temperatures. Back up generators. Ample ventilation. Humidifier should keep humidity above 50.
LC
Lucent Connector. A newer style of SFF fiber-optic connector that's pulling ahead of the MT-RJ. Uses a ceramic insert just as standard-sized fiber-optic connectors do.
tapping
Extracts signal from an optical fiber without breaking the connection.
broadcast storm
Extreme amounts of broadcast traffic. A broadcast storm can consume sufficient network resources so as to render the network unable to transport normal traffic.
multicasting
Group communication where information is addressed to a group of destination computers simultaneously. Uses routers and switches.
What happens if the humidity in a room housing compute hardware is not within the right range?
If it is too dry, static electricity will build up in the air, making the situation ripe for damaging a system. If it is too damp, connections start corroding and shorts begin to occur.
PSTN
Public switched telephone network. The world's collection of interconnected voice-oriented public telephone networks, both commercial and government-owned. It's also referred to as the Plain Old Telephone Service (POTS).
RFI
Radio Frequency Interface.
repeater
Receives a digital signal, reamplifies or regenerates that signal, and then forwards the digital signal out all active ports without looking at any data.
bus
Related to the Latin "omnibus", meaning "for all." Is a communication system that transfers data between components inside a computer, or between computers.
V. 35 physical interface
The serial interface routers use for WAN connections.
broadcast domain
The set of all devices on a network segment that hear all the broadcasts sent on that segment.
plenum
The space between floors in many large multistory buildings designed to circulate air through the spaces between the ceiling of one story and the floor of the next. Often used to run cables.
What can the other NIC LED's indicate?
The speed of the connection: 10, 100, or 1000 Mbit/ sec. The NIC is receiving a proper signal from the hub or switch. Connectivity to and detection of a carrier on a segment. connectivity with a router or other end device using a crossover cable.
latency
The time measured from when a frame enters a port to when it exits.
What are the advantages of using dedicated encryption devices?
They normally provide more choice of encryption methods and stronger encryption options. They also offload the process from other devices like routers and servers. The encryption /decryption process is very processer intensive and interferes with other functions that those routers and servers might be performing. Sometimes called encryption gateways.
Name the primary cable properties.
Transmission speed Distance Duplex Noise immunity Frequency
fiber-optic cable
Transmits digital signals using light impulses rather than electricity, and therefore is immune to EMI and RFI.
What are the benefits of using dedicated appliances for certain services?
Using appliances to offload functions such as encryption, content filtering, and VPN concentration can decrease the workload of other systems and add functionality that may be present in these dedicated devices.
What is the maximum USB connectors you can have?
Usually get a maximum of 4 external USB interfaces. With add-on adapters can take that up to as many as 16 serial interfaces. Can connect a maximum of 127 external devices using chained together hubs.
web proxy server
Usually used to create a web cache. The web proxy "remembers" you, and the site not only loads faster, it sometimes even recalls your personal information by automatically filling in your username— or even your billing/ shipping information when you place another order.
When are LC connectors used?
With Fibre-Channel adapters (FCs), fast storage area networks and Gigabit Ethernet adapters.
How do you attach a BNC to a cables?
With a crimper and a crimper die.
Can you tap fiber optics?
Yes, but it is much harder. You have to cut and repair the cable.
Do routers have operating systems?
Yes. They are like CPUs that are totally dedicated to the process of routing packets.
domain names
.org, .gov., .edu, etc.
UTP Gigabit Wiring (1000BaseT)
1000BaseT UTP wiring requires four wire pairs and uses more advanced electronics so that each and every pair in the cable can transmit simultaneously.
What are the parameters of a 110 block?
110 blocks come in sizes from 25 to more than 500 wire pairs, and some are capable of carrying 1Gpbs connections when used with Category 6 cables. However, using Cat 6 with the 110 block is difficult because of the size of the Cat 6 wiring.
What are the primary types of Ethernet wiring standards?
568A 568B Straight-through Crossover Rolled/ rollover
What is the maximum length twisted pair cable should be used?
328 feet (100 meters).
What are the different types of name resolution?
A HOSTS file (meaning you statically type in all names and IP addresses on each and every host). A request broadcast on the local network. DNS (Domain Name Service or Server). Most popular is DNS. Microsoft's Windows Internet Naming Service (WINS).
proxy server
A computer that offers a computer network service to allow clients to make indirect network connections to other network services. A client connects to the proxy server, then requests a connection, file, or other resource available on a different server.
half-duplex communication
A device can either send communication or receive communication, but not both at the same time, such as a walkie-talkie.
VPN concentrator
A device that accepts multiple VPN connections from remote locations.
transparent bridge
A network device that connects two similar network segments together. Its primary function is to keep traffic separated on either side of the bridge, breaking up collision domains. Traffic is allowed to pass through the bridge only if the transmission is intended for a station on the opposite side. Software based.
router
A network device used to connect many, sometimes disparate, network segments together, combining them into an internetwork.
NIC
A network interface controller (also known as a network interface card, network adapter, LAN adapter or physical network interface) is a computer hardware component that connects a computer to a computer network.
subnet
A part of a larger network such as the Internet.
redundancy
A process through which additional or alternate instances of network devices, equipment and communication mediums are installed within network infrastructure. It is a method for ensuring network availability in case of a network device or path failure and unavailability.
caching proxy server
A proxy server that speeds up the network's service requests by recovering information from a client's or clients' earlier request. Caching proxies keep local copies of the resources requested often, which really helps minimize the upstream use of bandwidth. These servers can greatly enhance network performance.
patch cable
A relatively short section (usually between 3 and 25 feet) of cabling with connectors on both ends.
What is the difference between the functions that a router interface and a switch interface perform?
A router interface will break up collision domains just as a switch interface does, but the purpose of a router interface is to create and maintain broadcast domains and connectivity of WAN services. Basic Layer 2 switches cannot provide these services. Router interfaces do not just work when you plug them into the network— they must be configured and enabled. All ports are shut down by default,
fault tolerance
A setup or configuration that prevent a computer or network device from failing in the event of an unexpected problem or error.
connectivity device
A specialized device that allows multiple networks or multiple parts of one network to connect and exchange data.
What are the two types of firewalls?
A stand-alone "black box" A software implementation placed on a server or router.
What duplex are switch ports set to?
All switch ports are set to duplex auto by default.
What can be employed as a DHCP server?
All types of hardware including routers.
How are NIC's connected?
Almost all NICs are built into the computer motherboard providing 10, 100, and 1000 Mbits/ sec. NIC adapters can be connected to the USB port or through a PC card slot.
main distribution frame (MDF)
Also called a main frame. A signal distribution frame for connecting equipment (inside plant) to cables and subscriber carrier equipment (outside plant). Also considered the WAN termination point.
smart jack
Also called a network interface device (NID) or network interface unit (NIU). A special network interface that's often used between the service provider's network and the internal network. May provide for code and protocol conversion, making the signal from the service provider usable by the devices on the internal network like the CSU/ DSU.
What is the difference between IDS and IPS?
An IDS is considered monitor mode and just records and tells you about problems, whereas an IPS can work in real time to stop threats as they occur. IPS prevent and block intrusions that are detected based on the rules you set up. IPSs can send an alarm, create correlation rules and remediation, drop malicious packets, provide malware protection, and reset the connection of offending source hosts.
demilitarized zone
An intermediary network of servers and equipment that can be considered both public and private (like web and email servers).
packet shaper
An internetworking traffic management technique that delays some or all packets to bring them into compliance with your or your company's traffic profile. Also known as traffic shaping. A form of rate limiting.
baseband
Analog or digital data before being intermixed with other data.
APC
Angle Polished Connector. Ideal for video and single fiber applications. Doesn't cause as much db loss.
full-duplex communication
Both devices can send and receive communication at the same time. Effective throughput is doubled and communication is much more efficient. Used in most of today's switched networks.
What are the National Fire Protection Association's (NFPA) requirements for cable run in the plenum?
Cable must be tested, guaranteed safe, fire retardant and create little or no smoke and poisonous gas when burned.
riser cable
Cable that is run between floors in non-plenum areas is rated as riser cable. The fire requirements on riser cable are not as strict. Thus, plenum cable can always replace riser cable, but riser cable cannot replace plenum cable in plenum spaces.
What is the minimum category any cable installed today should be and why?
Cat 5e. Because some cable is now certified to carry bandwidth signals of 350MHz or beyond. This allows unshielded twisted-pair cables to exceed speeds of 1Gbps— fast enough to carry broadcast-quality video over a network.
What was the standard cable used in the North American telephone service before 1983?
Cat1.
What do routers do?
Connect networks together and route packets of data from one network to another. Break up a broadcast domain. Switches do not. Provides connections to WAN services.
How do you connect a crossover Ethernet cable?
Connected pins 1 to 3 and 2 to 6 on each side of the cable.
subscriber (or square) connector (SC)
Connector that is latched (a mechanism holds the connector in securely and prevents it from falling out). SC connectors work with both single-mode and multimode optical fibers and will last for around 1,000 matings.
25-pair cable
Consists of 25 individual pairs of wires all inside one common insulating jacket. Used for telephone cabling, and especially for backbone and cross-connect cables because it reduces the cable clutter.
What are the layers of fiber optic cable?
Core. Cladding. Flexible plastic buffer. Armor coating usually made of Kevlar. Sheath of PVC or plenum.
Why would you use non-plenum cable?
Cost.
reservation list
Created so that a host always receives the same IP address.
cable tester
Device used to check the functionality of network cables.
DB-25
DB-25 tells us we have 25 pins in a "B" size shell. Connector part of the D series. Obsolete.
network adaptor
Devices installed in network nodes that enable the nodes to communicate with each other and to access the network.
DCE
Data Communication Equipment or Data Carrier Equipment. Usually, the DTE device is the terminal (or computer), and the DCE is a modem.
DNS
Domain Name Service or Server. A hierarchical way of associating domain names with IP addresses. Allows you to use internet site name rather than IP addresses.
dynamic DNS
Dynamic DNS is a method of automatically updating a name server in the Domain Name System (DNS), often in real time, with the active DNS configuration of its configured hostnames, addresses or other information.
DHCP
Dynamic Host Configuration Protocol. The service on your network that automatically assign IP addresses to hosts and to helps prevent the same address from being assigned to two different hosts.
static IP addressing
Each host is given an IP address manually. As opposed to Dynamic Host Configuration Protocol Server.
What is the difference between using fiber optic cable that uses either a glass or plastic core?
Glass can carry the signal a greater distance, but plastic costs less.
How do you connect a straight through Ethernet cable?
Four wires are used in straight-through cable to connect 10/ 100 Ethernet devices. Only pins 1, 2, 3, and 6 are used. Connect 1 to 1, 2 to 2, 3 to 3, and 6 to 6. Doesn't work with 1000Mbps Ethernet, voice, Token Ring, ISDN, etc.
FQDN
Fully qualified domain name (FQDN). An FQDN consists of a hostname and a domain name.
switch
Hardware-based, multiport bridge. The terms bridge and switch are often used interchangeably. A faster, smarter bridge that has more ports.
HIDS
Host-based IDS. Software runs on one computer to detect abnormalities on that system alone by monitoring applications, system logs, and event logs— not by directly monitoring network traffic.
What are the problems associated with using non-plenum cables?
In case of fire, the non-plenum cable becomes a hazard because its insulation gives off poisonous smoke that gets circulated throughout the entire building. Can also become "wicks" for the fire, helping it quickly spread from room to room and floor to floor.
Activity LED
Indicates the intermittent transmission and reception of frames arriving at the network or leaving it.
crosstalk
Interference caused when electromagnetic signals are conducted on copper wires in close proximity, like inside a cable.
IDS/IPS
Intrusion detection systems (IDSs) and intrusion prevention systems (IPSs). Network security appliances that monitor networks and packets for malicious activity.
Layer 3 switch
Is actually a router. Routers, Layer 3 switches, and multilayer switches are all names for routers.
How can you avoid EMI?
Keep copper cables away from all powerful magnetic sources like electric motors, speakers, amplifiers, fluorescent light ballasts, etc.
Ethernet cable unique identifiers
L = link B = backbone P = passive.
What is the best network design?
LAN switches with routers, correctly placed in the network.
link-light
LED that is usually green. Indicates that an Ethernet connection has been established with the device on the other end of the cable. Flickers when traffic is being passed back or forth.
Which layer are switches?
Layer 2 device. They segment the network with MAC addresses.
What do Layer 2 and Layer 3 devices need to locate?
Layer 3 machines (such as routers) need to locate specific networks, whereas Layer 2 machines (switches and bridges) need to eventually locate specific devices.
What are some load balancing parameters that can be set?
Least load. Fault tolerance. The fastest response times. Dividing up (balancing) outbound requests for smooth network operations.
What are the light sources used with SMF?
Light-emitting diodes (LEDs) and laser.
What types of records can only be created manually?
MX and CNAME.
MX
Mail exchanger records. Used to translate mail records. The MX record points to the mail exchanger for a particular host.
What is the main purpose of a switch?
Make a LAN work better better— to optimize its performance— providing more bandwidth for the LAN's users.
What can a router do?
Make intelligent decisions about the best way to get network data to its destination. It gathers the information it needs to make these decisions based on a network's particular performance data.
Mpbs
Mbps, short for megabits per second, a measure of data transfer speed.
analog modem
Mo dulator-dem odulator. A device that modulates an analog carrier signal to encode digital information and demodulates the signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. These signals are transmitted over telephone lines and demodulated by another modem at the receiver side in order to read the digital data.
MLS
Multilayer switch. A computer networking device that switches on Open Systems Interconnection (OSI) Layer 2 like an ordinary network switch but provides routing.
MMF
Multimode Fiber. Uses multiple rays of light simultaneously, with each ray running at a different reflection angle to carry the transmission over short distances. MMF provides high bandwidth at high speeds over medium distances (up to about 3,000 feet).
What is the major difference between a router interface and a switch interface configuration?
On a switch, you do not add an IP address since they only read to Layer 2 or usually configure a switch interface. They are enabled by default, they are good at auto-detecting the speed, duplex, and in newer switches, even the Ethernet cable type (crossover or straight-through). On a router, an IP is expected on each interface, they are not enabled by default, and a good Layer 3 network design must be considered before installing a router.
collision domain
On an Ethernet network, the portion of a network in which collisions occur if two nodes transmit data at the same time.
What are the two primary network connections of a firewall?
One to the Internet (known as the public side). One to the network (known as the private side).
What are some router functions in your network?
Packet switching. Packet filtering. Internetwork communication. Path selection.
What is the difference between the 568A and the 568B?
Pairs 2 and 3 (orange and green) are swapped. Pins 4, 5, 7, and 8 aren't used in either standard sometimes. Except with Voice over IP (VoIP)?
What is the topology of a hub in an Ethernet environment?
Physical star/ logical bus. Simulates the physical bus that the CSMA/ CD standard was based on.
PTR
Pointer Record. The DNS client queries DNS with the IP address. The server responds with a name. They reside in what is called a reverse lookup zone (or table) on the server.
Which plastics are commonly used to cover the braided shield of coaxial cable?
Polyvinyl Chloride (PVC). Fofluoroethylenepropylene (FEP, commonly known as Teflon and often referred to as plenum-rated coating).
PIDS
Protocol based intrusion detection system. Monitors traffic for one protocol on one server.
scope options
Provide IP configuration for hosts on a specific subnet.
Facts about routers that should be memorized.
Routers, by default, will not forward any broadcast or multicast packets. Routers use the logical address in a Network layer header to determine the next hop router to forward the packet to. Routers can use access lists, created by an administrator, to control security on the types of packets that are allowed to enter or exit an interface. Routers can provide Layer 2 bridging functions if needed and can simultaneously route through the same interface. Layer 3 devices (routers, in this case) provide connections between virtual LANs (VLANs). Routers can provide quality of service (QoS) for specific types of network traffic.
content filtering appliance
Scans the content of what goes through it and filters out specific content or content types.
Why is it better to use a crimper than a screw on connector?
Screw on connectors are not very reliable.
load balancing router
Sends incoming packets to multiple machines hidden behind one IP address.
serial cables
Serial means that one bit after another is sent out onto the wire or fiber and interpreted by a network card or other type of interface on the other end. Everything so far except multimode fiber.
demarc
Short for demarcation. The last point of responsibility for the service provider. It's often at the MDF in your building connection. Usually an RJ-45 jack that your channel service unit/ data service unit (CSU/ DSU) connects from your router to wide area network (WAN) connections.
SNMP
Simple Network Management Protocol. An application-layer protocol defined by the Internet Architecture Board (IAB) in RFC1157 for exchanging management information between network devices. It is a part of Transmission Control Protocol⁄Internet Protocol (TCP⁄IP) protocol suite.
SMF
Single-mode fiber. A very high-speed, long-distance media that consists of a single strand— sometimes two strands— of glass fiber that carries the signals. can transmit data 50 times further than multimode fiber at a faster rate.
SOHO router
Small office home office router.
What are the benefits of the MT-RJ fiber-optic connector?
Small size TX and RX strands in one connector Keyed for single polarity Pre-terminated ends that require no polishing or epoxy Easy to use
How do you connect a UTP Gigabit Wiring (1000BaseT) cable?
Straight-through cable = 1 to 1, 2 to 2, and so on up to pin 8. Crossover cable = 1 to 3 and 2 to 6, but you would add 4 to 7 and 5 to 8.
feeder cable
Supplies signal to many connected pairs. Often 25-pair cable is called this.
What devices are connected by crossover Ethernet cable?
Switch to switch (typical) Hub to hub Host to host Hub to switch Router direct to host Can also be used to test communications between two workstations directly, bypassing the switch. Used only in Ethernet UTP. Connect two workstation NICs or a workstation and a server NIC directly with it.
What is the difference between switches and routers.
Switches create separate collision domains but a single broadcast domain. Routers provide a separate broadcast domain for each interface.
unmanaged switch
Switches that can perform the basic switching process and do not allow you to configure more advanced features— like adding an IP address for telnetting to the device or adding VLANs.
managed switches
Switches that do allow an IP address to be configured for management with such applications as SNMP and do allow special ports to be configured (as in VoIP).
Why can you describe an AP as being like a hub?
The AP creates one collision domain and can only run half duplex.
Which LED should be verified first and why?
The Link LED because if it's not illuminated, the Activity LED cannot illuminate.
network segmentation
The act of splitting a computer network into subnetworks, each being a network segment. Advantages of such splitting are primarily for boosting performance and improving security.
hostname
The actually (mostly alphabet) name of a device that has a specific IP address.
scalability
The capability the network or process to handle a growing amount of work, or its potential to be enlarged in order to accommodate that growth.
frequency
The capacity to carry the signal in a cable. Each cable type has a specified maximum frequency that gives you the transmission bandwidth it can handle. Ex. Cat 5e cable is tested to 100MHz maximum frequency and can run 1Gbps signals for relatively short distances maxing out. Cat 6 is a 250MHz cable that can handle 1Gbps data flow all day long with ease.
How does a DHCP provide IP addresses to host that aren't on the same LAN?
The router interface can be configured to relay or forward the DHCP client requests.
attenuation
The degradation of a signal due to the medium itself and the distance signals have to travel.
hub
The device that connects all the segments of the network together in a star topology Ethernet network. Any transmission received on one port will be sent out all the other ports in the hub, including the receiving pair for the transmitting device. Do not use in corporate environments.
lease time
The fixed duration of the DHCP IP address.
568A
The green pair is used for pins 1 and 2 but the orange pair is split to pins 3 and 6, separated by the blue pair.
demarc extension
The length of copper or fiber that begins after the demarc but still doesn't reach all the way up to your office.
magnetic flux
The magnetic current caused by electrons being pushed through two wires next to each other.
bandwidth
The maximum amount of data that can pass from one point to another in a unit of time.
568B
The orange pair is pins 1 and 2 and the green pair is pins 3 and 6, again separated by the blue pair.
What is the major difference between the packet-switching operation of a router and that of a Layer 3 or multilayer switch?
The physical implementation. In routers, packet switching takes place using a microprocessor, whereas a Layer 3 switch handles this by using application-specific integrated circuit (ASIC) hardware.
serial interface
The physical interface through which information transfers in or out one bit at a time (in contrast to a parallel port).
name resolution
The process of finding the IP address for any given hostname.
Fiber to Coaxial
These devices accept a fiber connector and a coaxial connector and convert digital signals from optical to coax.
Multimode Fiber to Ethernet
These devices accept a fiber connector and an Ethernet connector and convert the signal from Ethernet and multi-mode fiber.
Why are HIDS typically implemented on servers?
They are difficult to manage if spread across several client computers on a network. If the IDS database is on the local computer and its data becomes compromised by an attack, the IDS data could be corrupted, too.
How do encryption devices work?
They can either sit in line with a server or a local network, encrypting and decrypting all traffic, or function as an application server, encrypting any file sent to them within a network.
What are the two advantages of using routers in your network?
They don't forward broadcasts by default. They can filter the network based on Layer 3 (network layer) information (such as an IP address).
What are the main reasons you would place a bridge in your network?
To connect two segments together or to divide a busy network into two segments. Not often used.
Why do you test for connectivity on both sides of the demarc/demarc extension?
To see if the problem is external or internal.
USB
Universal Serial Bus. An industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication, and power supply between computers and electronic devices.
What are standard transmission speeds?
Up to 10Gbps or higher on the core areas of the networks that connect various network segments. 100Mbps per connection in the distribution and access areas where users connect to switches.
What are some requirements for using thinnet cable?
Use BNC connectors to attach stations to the network. Use 50 ohm terminating resistors at each end of the cable in order to achieve the proper performance.
straight through Ethernet cable
Used to connect a host or a router to a switch or hub.
When would you use a second firewall?
Used to connect servers and equipment that can be considered both public and private (like web and email servers).
rolled cable
Used to connect your PC, Mac, or a device like an iPad to the Cisco hardware. Used to connect a host EIA-TIA 232 interface to a router console serial communication (COM) port. Eight wires are used in this cable to connect serial devices, although not all eight are used to send information, just as in Ethernet networking.
What is a media converter?
Used to go from one mode of fiber to another mode, to go from fiber to Ethernet.
What is the purpose of a packet shaper?
Used to optimize or guarantee performance, improve latency, and/ or increase usable bandwidth for some kinds of packets by delaying other kinds, as configured by the administrator.
T1 crossover cable
Used to run a cable between two CSU/ DSUs. A T1 cable uses T568B pairs 1 and 2, so to connect two T1 CSU/ DSU devices back-to-back requires a crossover cable that swaps these pairs. Specifically, pins 1, 2, 4, and 5 are connected to 4, 5, 1, and 2, respectively.
VPN
Virtual Private Network.
Single-Mode Fiber to Ethernet media converter
These devices accept a fiber connector and an Ethernet connector and convert the signal from Ethernet and single-mode fiber.
Single-Mode to Multimode Fiber
These devices accept a single-mode fiber connector and a multimode fiber connector and convert the signals between the two.
How do you minimize crosstalk?
Twist two wires together as a pair.
shielded twisted pair cable (STP)
Twisted pair cable with a metallic shield placed around it.
unshielded twisted pair (UTP) cable
Twisted pair cable without a metallic shield placed around it.
When is unshielded twisted pair used?
Twisted-pair Ethernet (10BaseT, 100BaseTX, 1000BaseTX) networks.
What does T stand for in an Ethernet cable type code?
Twisted-pair.
Category 6a (Augmented)
p. 62 Who the hell knows.
coaxial cable specifications table
pg. 59
RX
receive
TX
transmit
What are the limits of copper cable?
1,500 feet without electronics regenerating the signal. The standards limit UTP to 328 feet.
10BaseFL
10Mbps, baseband, over fibre optic cable (L is for link) specification. An Ethernet network that uses fibre optic cable to connect computers and repeaters. The maximum distance for a 10BaseFL segment is 2000 metres (about 6500 feet). The 100Mbps version of this implementation is 100BaseFX.
F connector
A coaxial RF connector commonly used for "over the air" terrestrial television, cable television and universally for satellite television and cable modems, usually with RG-6/U cable or, in older installations, with RG-59/U cable.
IEEE 802.3
A collection of IEEE standards produced by the working group defining the physical layer and data link layer's media access control (MAC) of wired Ethernet. This is generally a local area network technology with some wide area network applications. Physical connections are made between nodes and/or infrastructure devices (hubs, switches, routers) by various types of copper or fiber cable.
broadband
A high-capacity transmission technique using a wide range of frequencies, which enables a large number of messages to be communicated simultaneously.
What are the outer layers of fiber optic cable?
A layer of flexible plastic buffer goes around the cladding that can be wrapped in an armor coating that's usually Kevlar, which is then sheathed in PVC or plenum.
cladding
A special material used to line the core of the MMF fiber optic cable and focus the light back onto it.
What is the wire standard for the standard for Gigabit Ethernet over UTP?
All four pairs (eight wires) of 5e be in good condition.
small form factor (SFF) connector
Allows more fiber-optic terminations in the same amount of space than its standard-sized counterparts.
field assembly connector
Also called the ferrule connector. Not popular but still used in telecommunications and measurement equipment with single-mode lasers. Looks identical to ST connectors.
coaxial cable
Also know as coax. Contains a center conductor made of copper that's surrounded by a plastic jacket with a braided shield over it.
thick ethernet
Also referred to as thicknet or 10BASE5. RG-8, about 1/ 2" in diameter, and also required 50 ohm terminating resistors on each end of the cable. The original commercially available variant of Ethernet.
thin ethernet
Also referred to as thinnet or 10Base2. A thin coaxial cable that is only 5 mm, or 2/ 10″ diameter. Radio Grade 58/RG-58.
What are the three most popular types of cabling used in modern networking designs?
Coaxial Twisted-pair (shown) Fiber optic
twisted pair cables
Consists of multiple individually insulated wires that are twisted together in pairs.
DTE
Data Terminal Equipment. A network "terminal," such as a desktop, server, or actual terminal.
db
Decibels. Loss in fiber optic cable.
straight tip (ST) connector
Developed by AT& T. One of the most widely used fiber-optic connectors. Uses a BNC attachment mechanism similar to thinnet's that makes connections and disconnections fairly frustration free.
When do you use RJ-11?
Digital Subscriber Line (DSL) connections.
How does a serial cable work?
Each 1 or 0 is read separately and then combined with others to form data. Different from parallel communication where bits are sent in groups and have to be read together to make sense of the message they represent.
What does the glass or plastic cladding do that surrounds the core of fiber optic cable?
Each has a different refraction index that reflects the light back into the core.
EMI
Electromagnetic interference a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. The disturbance may degrade the performance of the circuit or even stop it functioning.
Ethernet
The most common form of LAN data transmission technology and follows the IEEE 802.3 standard.
What are best practices for connecting cable?
Ensure that all components are rated to deliver what they should (for 5e faster than 10Mbps over UTP). Do not stretch the number of twists inside the jacket. Connect and test all wires.
Category 3
Four twisted wire pairs (eight wires) with three twists per foot. This type can handle transmissions up to 16MHz. It was popular in the mid-1980s for up to 10Mbps Ethernet, but it's now limited to telecommunication equipment and, again, is obsolete for networks.
Category 5e (Enhanced)
Four twisted wire pairs (eight wires), rated for 100MHz but capable of handling the disturbance on each pair that's caused by transmitting on all four pairs at the same time— a feature that's needed for Gigabit Ethernet. Any category below 5e shouldn't be used in today's network environments.
Category 5
Four twisted wire pairs (eight wires), rated for 100MHz. Better to use 5e. It is the same price.
Category 4
Four twisted wire pairs (eight wires), rated for 20MHz; also obsolete.
Category 6
Four twisted wire pairs (eight wires), rated for 250MHz. Best for installing a new network in a new building. Maybe.
Category 2
Four twisted wire pairs (eight wires). It handles up to 4Mbps, with a frequency limitation of 10MHz, and is now obsolete.
What are the advantages of LC connectors?
Has similar advantages to MT-RJ and other SFF-type connectors but it's easier to terminate.
When is coax used?
High-bandwidth runs in data centers. Only used now with - RG-6, or CATV coax, is used in broadband. RG-59/U in older installations.
Why is plenum-rated coating often required, despite its higher cost?
It is often required by by local or municipal fire code when cable is hidden in walls and ceilings.
Why is twisted pair the most common type of cable used?
It's cheaper than other types of cabling. It's easy to work with. It allows transmission rates that were impossible 10 years ago.
What are the pros of fiber optic cable?
It's completely immune to EMI and RFI. It can transmit up to 40 kilometers (about 25 miles). Doesn't create a readable magnetic field.
What are the cons of fiber optic cable?
It's difficult to install. It's more expensive than twisted-pair. Troubleshooting equipment is more expensive than twisted-pair test equipment. It's harder to troubleshoot.
What is the code for Ethernet cable types?
N < Signaling > X N = the signaling rate in megabits (Mb) per second. < Signaling > = the signaling type— either baseband or broadband. X = a unique identifier for a specific Ethernet cabling scheme.
POTS
Plain old telephone service. Another term for Cat1 cable.
RS-232
Recommended Standard 232 (RS-232). Was a cable standard commonly used for serial data signals connecting the DTE and the DCE, such as a computer's serial port to an external modem. These cables normally connect to a connector on the device called a DB-9. Obsolete.
How do you connect UTP cable?
Registered jack (RJ) connector. Also what telephones use. Uses a crimper with a different die.
RJ-45
Registered jack connector for eight wires/four wire pairs. Used in LANs with short distances (typically up to 100 meters). Unshielded.
RJ-11
Registered jack connector for four wires/two wire pairs.
What is the difference in materials between SMF and MMF?
SMF uses glass. MMF used glass or plastic.
BNC connectors
The BNC (Bayonet Neill-Concelman) connector is a miniature quick connect/disconnect radio frequency connector used for coaxial cable. It features two bayonet lugs on the female connector. Mating is fully achieved with a quarter turn of the coupling nut.
What is the advantage of using a coax cable?
The braided shielding that provides resistance to electronic pollution like electromagnetic interference (EMI), radio frequency interference (RFI), and other types of stray electronic signals that can make their way onto a network cable and cause communication problems.
mechanical transfer registered jack (MT-RJ or MTRJ)
The first small form factor fiber-optic connector to be widely used, and it's only one-third the size of the SC and ST connectors it most often replaces.
return loss
The loss of db caused from the light being reflected back down to the core of the fiber cable from using UPC.
What are the two most popular small form factor connectors?
The mechanical transfer registered jack (MT-RJ or MTRJ), designed by AMP, and the Local Connector (LC), designed by Lucent.
Category 1
Two twisted wire pairs (four wires). It's the oldest type and is only voice grade— it isn't rated for data communication. Still exists in parts of the Public Switched Telephone Network (PSTN) and supports signals limited to the 1MHz frequency range.
UPC
Ultra-Polished Connectors. End is perfectly straight.
RJ-48c
Used with a T1 connection, which is a long-distance wide area network (WAN). Typically shielded.
Mbps
When spelled Mbps, short for megabits per second, a measure of data transfer speed (a megabit is equal to one million bits). Network transmissions, for example, are generally measured in Mbps. When spelled MBps, short for megabytes per second.
