Messer - 2. Infrastructure Flashcards

Question

Unlike copper cable, which communicates via _______, optical fiber communicates via ________.

Answer 1

electrical signal | wavelengths of light (i.e. visible spectrum)

Answer 2

1) Sending electrical signal over copper creates radio frequency (RF) interference that is easy to tap / monitor 2) Copper is vulnerable to RF interference from outside 3) Fiber can transmit over longer distances (i.e. kilometers v. hundreds of meters) because light signal slower to degrade than electrical

Answer 3

Multimode fiber: - Short-range communication (up to 2km) - Inexpensive light source (i.e. LED) Single-mode fiber - Long-range communication (up to 100 km w/o processing) - Expensive light source (i.e. laser) [Careful: Easy to think "multi" means better]

Answer 4

Called multimode because core of fiber is larger than wavelength of light. As signal travels down fiber, it disperses and creates multiple modes (i.e. beams?) of signal. In single-mode, fiber is much narrower than core of multi-mode, allowing us to send light signal in a single, straight light beam. (Which is why signal degrades slower / travels further.)

Answer 5

Within the various types of fiber connectors (e.g. ST, SC, LC, MT-RJ, etc), you can choose ones that are either angle polished connectors (APC) or ultra polished connectors (UPC). UPC connectors have an endface polished at a zero-degree angle (flat), whereas APC is eight degrees, which minimizes signal loss. (Professor Messer uses analogy of pointing flashlight through a window. Pointing at an angle creates less reflection.) [Mike Meyers says the "P" in acronyms is technically "physical" rather than "polished"]

Answer 6

ST, SC, LC, MT-RJ

Answer 7

- aka. Straight Tip - Bayonet connector (push and half-twist to lock it in) - Rounded connector at end - Rather long ferrule that sticks out (easy to spot) [Think "ST" for "sticks out". But note that SC also sticks out a little]

Answer 8

-aka. Square / Subscriber / Standard Connector Push and pull out (no twisting like bayonet) -Plastic keys to ensure exact fit -Round Ferrule at end that sticks out a little [Remember "SC" sound for "square". But note that LC is also square, but with large flange on top]

Answer 9

- aka. "Little" / Lucent / Local Connector - Squarish but with large locking mechanism (similar to RJ-45) [Remember "L" for large flange on top. Although ironically called "Little Connector". Like a fat guy named "Little John," I guess]

Answer 10

- aka Mechanical Transfer Registered Jack or Media Termination - Recommended Jack - Very small form factor that fits two fibers (send and receive) - About the size of an RJ-45 connector (Ethernet) - Very popular [Unlike other fiber connectors, has two pins / prongs / ferrules instead of one]

Answer 11

Two wiring standards for terminating copper cables. T568B is what we use on today's networks

Answer 12

Pick one standard and stick to it. You can't terminate one side of the cable with 568A and other with 568B. Will cause problems, especially on Gigabit network. If you aren't consistent you might end up swapping the sending and receiving wires (known as TX/RX reversed) and inadvertently create a crossover cable.

Answer 13

Only difference is that GREEN and ORANGE wires are swapped in the two standards. (e.g. In 568A, pin 1 is white and green. In 568B, pin 1 is white and orange. Think "GO")

Answer 14

Straight-through cables are used to connect DIFFERENT types of devices (e.g. host to client, workstation to switch, hub to switch). Crossover cables are used to connect SAME types of devices (e.g. host to host, workstation to workstation, or switch to switch). Note: A crossover cable can be used to directly network two PCs without using a hub or switch. (The cable performs the function of the switch.) [Careful: A bit unintuitive that crossover is used for same type of device]

Answer 15

Place the connectors side-by-side facing the same direction. If wires are in same order on both connectors, it's a straight-through cable.

Answer 16

A feature on newer Ethernet devices (e.g. network cards, routers) which automatically detects whether incoming signal is straight-through or crossover, and adjust accordingly.

Answer 17

Found in a telecommunications closet, it's a freestanding or wall-mounted unit with a number of female (e.g. RJ-45) port connections on the front. (Looks like a wall-mounted hub w/o the LEDs.) On the back, a punchdown block with permanent connections to horizontal cabling. Often a 66 block or nowadays the more common 110 block. The patch panel provides a connection point between network equipment, such as hubs and switches, and the ports to which PCs are connected, which normally are distributed throughout a building.

Answer 18

You can run cables directly between systems and a hub or switch, but it's not as easy, flexible, or tidy. With a patch panel, you can simply move the RJ45 cable to appropriate place on switch / interface. If there's a new employee, you only need to add a new cable from patch panel to networking equipment. Makes moves, adds, and changes very easy. (You're also less likely to damage cabling by moving it.)

Answer 19

Punchdown tools are used to attach twisted-pair network cable to connectors within a patch panel. Specifically, they connect twisted-pair wires to the IDC.

Answer 20

66 blocks are generally used for voice and Cat3 data. 110 blocks are the newer, higher-speed technology, generally used for Cat5 and Cat6 data. They support higher frequencies and suffer less crosstalk. (66 blocks were approved for Cat5 and greater, but not really suitable for anything greater than 10BASE-T due to crosstalk problems. Although there are specialized exceptions.)

Answer 21

A fiber distribution panel (FDP). Like a patch panel, it's used to provide a connection point between network equipment. The difference between the two is that the FDP is a cabinet intended to provide space for termination, storage, and splicing of fiber connections.

Answer 22

Typically, the main distribution frame (MDF) is a closet / room that stores a building's demarc, telephone cross-connects, and LAN cross-connects. An intermediate distribution frame (IDF) room is what we typically think of as a telecommunications closet / room, which contains patch panels, punchdown blocks, and serves individual floors. (According to Meyers, these concepts are just ideals. Not always the case that you have a single MDF and multiple IDFs, or that these are even separate.) [These terms are not in Messer vids from what I can see]

Answer 23

Provides a modular interface for network devices, allowing them to easily adapt to various copper or fiber optic standards. Transceivers can be a stand-alone component (kinda looks like a thumb drive) that gets plugged into a device, or they may be built directly into a network card, switch, router, modem, media converter, etc. Called transceiver because it's responsible for both transmitting and receiving (i.e. it place signals onto network media and also detect incoming signals on same wire). [Not 100% sure how transceivers are different from media converters. From what I gather, media converters may contain an embedded transceiver]

Answer 24

Duplex communication - Two fibers. One transmits, other receives. Bi-Directional (BiDi) communication - Single fiber transmits and receives. Significant cost savings by cutting number of required fiber runs in half, but network must support it. [Careful: Naming may be a bit unintuitive here. ]

Answer 25

GBIC, SFP, SFP+, QSFP, QSFP+

Answer 26

Gigabit Interface Converter. An early transceiver standard commonly found on Gigabit and fiber channel networks. Offers both copper and fiber support.

Answer 27

Small Form-Factor Pluggable. Transceiver standard that replaced GBIC. Does the same thing, but smaller form-factor. SFP - Commonly used to provide 1 Gbit/s fiber. RJ45 SFPs also available w/ copper connectors SFP+ - Enhanced SFP w/ much higher data rates. Supports data rates up to 16 Gbit/s. Common with 10 Gigabit Ethernet.

Answer 28

Quad Small Form-Factor Pluggable. Transceiver standard for very high speed networking. Basically four SFPs put into a single transceiver, offering cost saving in fiber and equipment. QSFP - 4-channel SFP = Four 1 Gbit/s = 4 Gbit/s QSFP+ - 4-channel SFP+ = Four 10 Gbit/s = 40 Gbit/sec (Both also available with BiDi, adding additional efficiency)

Answer 29

``` 100BaseT 1000BaseT 1000BaseSX 1000BaseLX 10GBaseT ```

Answer 30

Gigabit Ethernet

Answer 31

Called "Fast Ethernet," because seemed fast compared to 10BaseT. New installs aren't using this anymore. Speed: 100 Mbps Distance: 100 meters (between hub/switch and node) Cable Type: Cat 5 or better UTP or STP (copper) cabling with RJ-45/8P8C connectors

Answer 32

Gigabit ethernet standard that most people are now using. Speed: 1000 Mbps (1 Gbps) Distance: 100 meters Cable Type: Cat5 or better UTP or STP (copper) (Cat 3, 4, and 5 are deprecated from TIA-568, so we now use Cat 5e) [Notice: Speed greater than 100BaseT, but cable type and distance are essentially the same. Speed difference in part because it uses all four pairs of wire instead of two]

Answer 33

One of the two fiber ethernet standards we need to know. Uses NIR (near infrared) light wavelength. 2-5x distance of copper. Speed: 1000 Mbps (1 Gbps) Distance: 200 meters to 500 meters, depending on fiber type Cable Type: Usually over multi-mode fiber [Think "S" for shorter wavelength light than LX, and shorter distance]

Answer 34

One of the two fiber ethernet standards we need to know. Uses long wavelength laser. 5.5-50x distance of copper. Speed: 1000 Mbps (1 Gbps) Distance: 550 meters (multi-mode) to 5 km (single-mode) Cable Type: multi-mode or single-mode fiber [Think "L" for laser, and longer wavelength light than SX, and longer distance]

Answer 35

High-throughput copper standard. Uses 500 MHz frequency inside cable, well above 125 MHz for Gigabit ethernet. [Note: Faster than earlier copper standards, but distance limitations remain the same] Speed: 10 Gbps Distance: 55 meters (Cat 6) or 100 meters (Cat 6A or Cat7) Cable type: Cat 6, 6A, or 7 [TIP: If standard ends in T, it's copper. At least for standards on the exam]

Answer 36

aka "Multi-port repeater" A rather primitive, obsolete networking device that directs data packets to all connected devices, regardless of whether the data is destined for that device. In other words, traffic into one port is repeated to every other port. A passive hub does nothing but pass along electrical signals, while an active hub regenerates the signal (and might provide some buffering).

Answer 37

Layer 1 - Physical (Because no forwarding decisions are made internally)

Answer 38

Doesn't make intelligent forwarding decisions and forwards all data to everyone, which is inefficient. Only allows half-duplex communication between devices (i.e. one direction at a time). Inefficient and can lead to a lot of collisions, especially as network speeds increase. Only works at 10 and 100 megabit/s. Doesn't work with gigabit ethernet.

Answer 39

A networking device that connects two local area networks, or connects network segments to form a larger network. Bridges got around some of the limitations of hubs by intelligently filtering and forwarding traffic between segments based on MAC addresses. This allowed larger networks with more devices, but without the hub's inefficiencies involving collisions. Bridges separate collision domains, but not broadcast domains. Can be used to connect different topologies (e.g. ethernet network to token ring network).

Answer 40

Layer 2 - Data Link

Answer 41

Wireless access point (which bridges wired ethernet to wireless ethernet)

Answer 42

Both forward traffic based on MAC address. Both therefore operate at OSI Level 2.

Answer 43

Bridges traditionally have 2 or 4 ports, while a switch might have hundreds of interfaces. Bridges use software to forward traffic, while a switch uses hardware (i.e. ASIC) for greater performance. Switches may provide Power over Ethernet (PoE) and other advanced features. Switches may be combined with routers in what are (erroneously) called "Layer 3 switches".

Answer 44

Application Specific Integrated Circuit An integrated circuit (IC) chip customized for a particular rather than general use. (e.g. a chip designed to forward packets in a switch, or to run a digital voice recorder, or a high-efficiency bitcoin miner)

Answer 45

A device that connects separate networks (or subnets) and forwards a packet from one to another using destination network address (i.e. IP address). Often connects diverse network types (e.g. LAN, WAN, copper, fiber)

Answer 46

Layer 3 - Network Layer

Answer 47

A device (or software) that restricts traffic (i.e. data access) between networks. Can encrypt traffic coming in and out of network. Can be configured as VPN endpoints at two locations. Can be configured as a proxy.

Answer 48

Really depends. Layer 3 - IP address filtering Layer 4 - TCP / UDP port filtering [traditional firewall] Layer 7 - applications (next generation firewalls)

Answer 49

Proxies tend to be used for specific things like anonymous web browsing. VPNs can and encrypt and secure ALL network traffic. [You know this. Just think about TorGuard]

Answer 50

A bridge that connects a wired network to wireless devices. And according to ExamCram book, can also act as a router passing data transmissions from one access point to another. [Need to be careful, because according to ExamCram book, an AP can act as a switch, DHCP server, router, and firewall. But I think this might be similar to "Layer 3 Switch" situation, where multiple devices are bundled into one?]

Answer 51

Layer 2 - Data Link [Remember, it's similar to a bridge / switch]

Answer 52

Modulator / demodulator. A network device that provides serial communication capabilities across phone lines by modulating the digital signal into analog at the sending end and performing the reverse function (i.e. demodulation) at the receiving end. Note: A cable modem is technically more of a bridge than a modem.

Answer 53

A device used to connect media that would otherwise be incompatible (e.g. copper and fiber). Ex. Can be used to extent a copper wire over a longer distance (e.g. by converting to fiber, then back again). Can be used if you have fiber, but switch only has copper ports. More ex. May be used to link fiber optic cable to twisted pair for supporting ethernet-compatible devices. May also link together networks comprised of coax cable, and single-mode to multi-mode fiber optic cable. ["Media" as in "physical media." Don't confuse w/ video]

Answer 54

Level 1 - Physical layer (signal conversion)

Answer 55

The receiving item for a VoIP network. This can be a handset, application, or server.

Answer 56

It's simply a switch (Layer 2) and a router (Layer 3) in the same physical device. It does NOT mean switching is suddenly happening at Layer 3.

Answer 57

A centralized management console, or single "pane of glass", from which you can manage wireless access points in bulk; add new access points; monitor performance, usage, and security; make bulk configurations, etc. Solves big problem of having to manage and configure numerous wireless access points individually. Usually a proprietary system (specific to the brand of access point you're using). The wireless controller is paired with the access points.

Answer 58

Load balancing is the process of distributing network traffic across multiple servers. This ensures no single server bears too much demand. By spreading the work evenly, load balancing improves application responsiveness. Through redundancy, also increases availability of applications and websites for users. Can be hardware or software. Multilayer switches and DNS servers can serve as load balancers. Can help with security (e.g. mitigating DoS attacks). Can provide TCP offload, SSL offload, caching, protocol prioritization, and content-switching where some apps have higher priority than others.

Answer 59

Intrusion Detection System / Intrusion Prevention System IDS is a passive detection system. Detects presence of an attack and then logs info. May also alert an admin to potential threat. IPS is an active/reactive security measure because it monitors and can then take steps to correct a potential security threat. [Some sources also saying that IDS looks at copies of traffic after the fact, whereas IPS looks at real-time traffic flow] [Btw, IPS can be standalone software like SNORT. But Messer says mostly found now in next generation firewalls]

Answer 60

False positives. You may not want a system automatically interfering with potentially legitimate activity. [Same reason I have my firewall set to alert me instead of automatically quarantining perceived threats. However, Messer says false positives aren't a big problem these days, and you mostly only see IPS rather than IDS]

Answer 61

Signature - Looks for a perfect match of a specific threat (e.g. Conifer worm) Heuristics - Looks for broad descriptions of general threat instead of a specific signature (e.g. uses AI) Anomaly - First builds baseline of what's "normal" on a network, then looks for anything outside that norm Behavior - Looks for specific actions to occur (e.g. if someone accesses a certain file) [Messer different than two books on this, but makes more sense]

Answer 62

Host-based IDS Host-based IPS Network-based IDS Network-based IPS Networked-based systems (NIDS / NIPS) examine incoming and outgoing network traffic. Can be hardware of software. Host-based systems (HIDS / HIPS) monitor activity on specific device or virtual machine (e.g. anti-virus software on a workstation).

Answer 63

* Host-based pros: - Can inspect data that may be encrypted / unassembled as it passes through network - May have vantage point / insights that are unavailable to network solutions * Host-based cons: - Are a bit late to the party. At this point, an attack has already passed network defenses. Malware can sometimes disable a host-based IDS or IPS. - Can be very cumbersome on a network with tons of hosts * Network-based pros: - Can catch problems before they ever get to the host (which ultimately requires for resources) - Cost-effective and easy to deploy (may require a lot to set up security on all hosts) - Still works even if a host is taken over by malware * Network-based cons: - Cannot inspect encrypted traffic (unless it's able to intercept and decrypt) - Can not tell if an attack has been successful (really need to be on host to know for sure)

Answer 64

A proxy is a device / server that sits between a client and an external network (e.g. the Internet). When a proxy receives a request from a client, it passes the request along as if that request originated from the proxy. The proxy then passes the response back to the client. Proxies can serve many purposes: caching, access control, URL filtering, content scanning, privacy, etc.) May be part of a firewall. Often written for one specific application (e.g. HTTP), although may be multi-purpose (e.g. HTTP, HTTPS, FTP, etc.).

Answer 65

A device that sits between a VPN client and VPN server, creates the tunnel, authenticates users using the tunnel, and encrypts data traveling through the tunnel. When the VPN concentrator is in place, it can establish a secure connection (tunnel) between the sending and receiving network devices. Can be stand-alone, but often integrated into a firewall. [Some are saying it's a type of router device, built specifically for creating and managing VPN communication infrastructures]

Answer 66

A security framework used to control who is permitted to use network resources (through authentication), what they are allowed to do (through authorization), and log the actions performed while accessing a network (through accounting). * Authentication - Prove you are who you say you are - Password, etc. * Authorization - Based on your identification and authentication, what access to resources do you have? (Rights and permissions granted based on username) * Accounting - Resources used: Login time, data sent and received, logout time [Two popular protocols / implementations are RADIUS and TACACS]

Answer 67

Remote Authentication Dial-In User Service | But not just for dial-in anymore

Answer 68

A security protocol that is based on the AAA framework and that operates as a client/server system to provide centralized authentication for users who want to gain access to a network, or devices on that network (e.g. allows using same credentials for routers, switches, firewalls, servers, VPN, etc). Supported on a wide variety of platforms and services [See also TACACS / TACACS+ in Security section] [Technically, Radius actually came before AAA]

Answer 69

Unified Threat Management

Answer 70

An approach to information security where a single hardware or software installation provides multiple security functions (e.g. firewall, IDS, IPS, proxy, email filtering, DLP, SIEM, VPN, etc.) [As I understand it, next-generation firewalls are a particular kind of UTM, but the two terms are apparently now interchangeable]

Answer 71

Simplifies installation, configuration, and maintenance. But also creates a single point of failure. If UTM is compromised, ALL your security is compromised.

Answer 72

Next-generation firewall

Answer 73

A firewall that operates at multiple layers of the OSI model. A traditional firewall that simply allowed / disallowed traffic based on TCP / UDP port number was only operating at Layer 4. Today's firewalls can filter packets based on IP address (Layer 3), or based on contents of application data (Layer 7). Layer 7 firewall requires some deep analysis: Every packet analyzed, categorized. Every bit, byte, and frame. Remember: a firewall is a device (or software) that restricts traffic (i.e. data access) between networks

Answer 74

Application layer gateway Stateful multilayer inspection deep packet inspection

Answer 75

The marriage between telephone technology and information technology. [Source: ExamCram. Still not entirely clear on this. And probably not on exam, just good to have in back of my mind.]

Answer 76

Historically, two terms essentially synonymous, with PSTN being official terminology, and POTS being more colloquial. But has evolved so that POTS now refers to method of last mile being an analog copper pair phone line (versus VoIP, for example). And PSTN simply refers to the national phone network as a whole, regardless of the method of last mile connection. (Similar to the word "Internet".)

Answer 77

Private Branch Exchange

Answer 78

Essentially, the internal telephone network of a business or other entity. PBX phone systems allow users to communicate with one another over the phone via internal lines, and make and receive external calls, as well. Connects to phone provider network. Legacy PBX systems used analog switchboards like the public switched telephone network (PSTN). Required analog telephone lines for each desk. Today, most PBX systems use digital networking protocols (IP).

Answer 79

A business telephone system that provides services similar to a standard PBX, but does so over a company’s LAN or WAN data network rather than through the circuit-switched networks used by the traditional Public Switched Telephone Network (PSTN). Also referred to as an IP PBX, VoIP PBX systems can typically switch calls between VoIP on local lines or between VoIP and traditional telephone users in the same way a PBX does. A VoIP PBX system can be hardware based or can function entirely as a software system. No longer need to run separate phone cables to every desk. VoIP devices can plug into ethernet connections.

Answer 80

A device that converts traditional PSTN protocols to and from VoIP protocols. Often built into the VoIP PBX. [So I guess this is what sits between the external PSTN network and the internal VoIP PBX network.]

Answer 81

Both vulnerable if there's an attack. [And I would say vulnerable to regular network outages, as well. At least in the case of home VoIP. And the quality suffers depending on various network variables.]

Answer 82

Any software that controls what a user is allowed to send and receive over a network. Often related to website access. Using a content filter, an employer can block access to pornographic sites. But can also be used to prevent the outbound flow of sensitive corporate information. The filter can be applied as software on client machines (known as client-side filters), on a proxy server on the network (a server-side filter), or at the Internet service provider (ISP). At home, can refer to parental controls.

Answer 83

Technology that allows consolidating many existing servers into one physical server and running each server in a virtual machine. The virtual machine uses resources such as random access memory (RAM) and hard disk space from the actual physical server.

Answer 84

More cost-effective because eliminates underutilized equipment. e.g. A lot of companies buy expensive servers, then fail to maximize their use of memory, processor, disk space, etc.

Answer 85

aka virtual machine monitor (VMM) The software component that allows you to create, run, and modify virtual machines. When you install the hypervisor on a system, that system is then known as the host system, while each virtual machine is known as a guest system. [Think "advisor" or "supervisor"]

Answer 86

Microsoft calls it Virtualization Technology (VT) | AMD calls it AMD-V

Answer 87

Network Attached Storage A device that provides file storage to systems on a network. The NAS is normally its own computing device that has multiple bays, multiple hard drives, and a redundant array of independent disks (RAID). This NAS device is then used as the file server for the network—a central place for everyone to store and access documents.

Answer 88

Storage Area Network A network that allows access to data storage devices, such as disk arrays and tape libraries from servers so that the devices appear to the operating system as direct-attached storage.

Answer 89

SAN - Block-level access (i.e. to change byte, you only write that block. Hard drives in PC work this way) - Looks and feels like a local storage device - Expensive compared to NAS (but much better if cost isn't an issue) NAS -File-level access (i.e. to change a single character in a file, you need to rewrite entire file) BOTH -Require a lot of bandwidth

Answer 90

Any frame that contains more than 1500 bytes of data (the default maximum size for Ethernet frames). Network devices can have Jumbo Frames enabled, which allows support for a maximum of 9216 bytes. (Although 9000 is accepted norm because more compatible with the usual 1500.) The advantage is that jumbo frames can reduce overhead / increase efficiency when sending large amounts of data because you have fewer frames or packets that need switching or routing. The disadvantage is that all ethernet devices between you and the network storage device need to support jumbo frames and have them enabled (e.g. switches, interface cards). And apparently, not all devices are compatible with others. [Note: I think Jumbo Frames are usually discussed in context of network storage]

Answer 91

Fiber channel (FC) FCoE iSCSI InfiniBand

Answer 92

A specialized, high-speed technology used to connect servers to storage over a network. (Offers connection speeds of -2-, 4-, 8-, and 16-gigabit per second.) Requires expensive, specialized equipment, including fiber channel switches, interfaces, and cables. Servers and storage connect to the Fiber Channel Switch. Server (initiator) needs a FC interface. Storage (target) is commonly referenced by SCSI, SAS (serial attached SCSI), or SATA commands using the Fiber Channel Protocol (FCP). [NOTE: Despite the name, supported over both fiber and copper]

Answer 93

Fibre Channel over Ethernet (FCoE) Allows you to use Fiber Channel over an Ethernet network without any special FC networking components (e.g. FC switch). It does this by encapsulating fiber channel frames inside an Ethernet frame. (Requires minimum 10 Gbps Ethernet.) Not routable, because done at Ethernet frame level. (I don't think you need to know this for exam, but Professor Messer mentioned Fiber Channel over IP (FCIP), a routable option for when you need to access storage on a different IP subnet. Encapsulates fiber channel data into IP packets instead of ethernet frames.)

Answer 94

A protocol that encapsulates SCSI commands in an IP packet so that the command can be sent across an Ethernet network from the server to the storage device. iSCSI allows you to use remote storage without having to invest in specialized hardware because you are able to use the existing Ethernet network. (Much cheaper!) Like Fiber Channel, makes a remote disk look and operate like a local disk. The storage space will run on an iSCSI target while the servers that wish to access this space will need to have the iSCSI initiator software to connect to the target. Created by IBM and Cisco. Now an RFC standard. Can be managed quite well in software, with drivers available for many OSes. No proprietary switches or adapter cards needed. [SCSI = Small Computer Systems Interface]

Answer 95

A newer, very high speed standard for connecting to storage over a network. Designed as an alternative to Fiber Channel. Uses either copper or fiber (w/ QSFP connections in the case of fiber). Popular in research and supercomputers. Designed for high speeds and low latency. 100 Gbit/sec and 200 Gbit/sec speeds are common. Links can be aggregated for higher throughputs (4x, 8x, 12x links) (i.e. those 100 and 200 Gbit/sec speeds can be multiplied).

Answer 96

Supervisory Control And Data Acquisition (SCADA) A special system used in industrial environments to monitor and control remote industrial equipment. SCADA is a form of industrial control system (ICS) that can monitor and manage equipment such as that at a production plant. [Messer doesn't cover in N10-007, although he does in N10-006. Still in glossary section of exam objectives]

Answer 97

``` ISDN T1/E1 T3/E3 Optical Carrier (OC) [SONET?] DSL/ADSL Metro Ethernet Cable Broadband Dial-Up ```

Answer 98

Integrated Services Digital Network A communication standard for sending voice and data over normal telephone lines or digital telephone lines. In order to connect to the ISDN lines, a system will need an ISDN modem, which doesn’t really act like a modem because whereas a modem converts digital data to analog, the ISDN modem carries digital data from one digital system to another. - Today, not usually seen as a sole, stand-alone WAN. But to support PBX - Commonly used as connectivity from the PSTN to large phone systems (PBX) - Also seen in radio / broadcasting services (support high quality audio between 2 locations)

Answer 99

Basic rate interface (BRI) This is a 128 Kbps connection that is made up of two 64 Kbps channels (known as Bearer or B-channels) and one 16 Kbps control channel (known as a D-channel). Primary rate interface (PRI) This is a 1.55 Mbps connection that is made up of twenty-three 64 Kbps channels (B-channels) and one 64 Kbps D-channel for signaling and control information [So basically, ISDN BRI is somewhere around 1 to 2x the speed of a 56k dialup modem. And ISDN PRI is around the speed of a T1 line]

Answer 100

"terrestrial carrier" T-carrier lines are high-speed dedicated digital lines that can be leased from telephone companies. T-carrier lines can support both voice and data transmissions and are often used to create point-to-point private networks. [Note that T1/T3 lines are circuit-switched. Carriers moved into more packet switched networking, like SONET]

Answer 101

T1 lines are a form of T-Carrier lines that offer transmission speeds of 1.544 Mbps. (Found in North America, Japan, South Korea). E1 refers to the European equivalent of T1, which offers a slightly faster 2.048 Mbps. [To put this in perspective, I just ran a speed test. Getting almost 100 Mbps download speed on Verizon's slowest plan]

Answer 102

T3 lines are a form of T-Carrier lines that offer transmission speeds up to 44.736 Mbps (using 672 64 Kbps B channels). E3 refers to the European equivalent of T3, which is quite a bit slower at 34.368 Mbps.

Answer 103

Synchronous Optical Network (SONET)

Answer 104

A fiber-optic WAN technology that delivers voice, data, and video at speeds between speeds of 51.84 Mbps and 9.95 Gbps. Created by Bell after AT&T monopoly ruling to standardize access methods for an ever-growing number of independent long-distance carriers. Involves packet switched networking as opposed to the circuit switched networking of T1 and T3. [See Optical Carrier (OC) numbers]

Answer 105

Introduced with SONET, these are levels that define data transmission rates.

Answer 106

Simply multiply the OC level by 52 Mbps, which is roughly the transmission rate for OC-1. e.g. For OC-3, you multiply 52 * 3 = 156. In addition to memorizing that OC-1 is 52 Mbps, might also be helpful to remember that OC-192 is roughly 10 Gbps.

Answer 107

``` OC-1 51.84 Mbps OC-3 155.52 Mbps OC-12 622.08 Mbps OC-24 1.244 Gbps OC-48 2.488 Gbps OC-96 4.976 Gbps OC-192 9.953 Gbps OC-768 39.813 Gbps ``` [It isn't clear from CompTIA's objectives if you only need to know OC-3 and OC-192, or everything in between. But to find the answer, you simply multiply the OC level by 52 Mbps, which is roughly the transmission rate for OC-1. And maybe just memorize that OC-192 is 10 Gbps.]

Answer 108

Asymmetric Digital Subscriber Line

Answer 109

A fully digital, dedicated (no phone number) connection. DSL represented the next great leap forward past ISDN for telephone lines. A physical DSL connection manifests as just another PSTN connection, using the same telephone lines and RJ-11 jacks as any regular phone line. With DSL, a different frequency can be used for digital and analog signals, which means you can talk on the phone while using the Internet. Typical download speeds for ADSL are as high as 9 Mbps and upload speeds around 1 Mbps. Speeds very depending on how close you are to the central office (CO). Limit seems to be between 5k and 10k. [I believe ADSL was originally a subset / advancement of DSL. Now DSL and ADSL are basically synonymous] [Books very inconsistent on the speeds. Different books mention different flavors: ADSL2, ADLSL2+, SDSL, IDSL, RADSL, VHDSL, HDSL. Unclear exactly what we need to know for this]

Answer 110

It's referring to the difference in download v. upload speeds. [Our Internet services have always been asymmetric. Very common in homes and small offices]

Answer 111

A metropolitan area network (MAN) created based on Ethernet standards. That is, a city-wide or regional network. Not your typical WAN connection. Uses ethernet instead of T1 or T3. Customers can use it as a method to gain Internet access or to connect multiple offices together. Usually a dedicated fiber line from the ISP to an office. Uses Ethernet rather than one of the remote connectivity options (like SONET or MPLS). Inside the provider's network, it could be pure ethernet, but usually running over a different topology. e.g. Ethernet over SDH, MPLS, or DWDM. [Again, kinda unclear]

Answer 112

Cable broadband Internet access is an always-on Internet access method available in areas that have digital cable television. Inexpensive and reliable. Often unlimited amounts of data, but speed is capped. Speeds of 4 Mbit/s through 250 Mbit/s are common. Gigabit speeds are possible. Uses a cable modem, which has a coaxial connection for connecting to the provider’s outlet and an unshielded twisted-pair (UTP) connection for connecting directly to a system or to a hub, switch, or router. Unlike ADSL, you do not need to be within close proximity of a central office (CO). But also unlike ADSL, you are sharing your bandwidth with those who live around you, theoretically impacting performance during peak-traffic times. [Key note: Some of the other high-speed Internet solutions were from phone company. This is cable television's answer.]

Answer 113

Whereas baseband uses digital signaling, broadband uses analog signals in the form of optical or electromagnetic waves over multiple transmission frequencies. For signals to be both sent and received, the transmission must be across multiple frequencies or channels.

Answer 114

Copper Fiber Wireless Satellite

Answer 115

Advantages: - Relatively inexpensive - Easy to install and maintain Disadvantages: - Limited bandwidth availability (physics limits electrical signals through copper) - Limited distance (at least compared to fiber)

Answer 116

Advantages: - Relatively inexpensive - Easy to install and maintain Disadvantages: - Limited bandwidth availability (physics limits electrical signals through copper) - Limited distance (at least compared to fiber)

Answer 117

Advantages: - High speed (very high data rates) - Greater distances than copper (because uses light rather than electric signal) - Can put a lot of customers on single strand of fiber - Usually supports SONET and wavelength division multiplexing [Okay?] Disadvantages: - More expensive than copper - More difficult to repair

Answer 118

Advantages: - Not tied to physical infrastructure (e.g. field service, travel) - Use an external hotspot or mobile phone to provide connectivity for our devices - Good for intermittent communication (e.g. Security system, daily point-of-sale reporting and updates) Disadvantages: - Coverage in remote areas can be a challenge (far from provider's antenna) - Speed limitations (although this might be changing. Some are suggesting this could replace wired ISP services)

Answer 119

Advantages: - Not tied to physical infrastructure (e.g. field service, travel) - Use an external hotspot or mobile phone to provide connectivity for our devices - Good for intermittent communication (e.g. Security system, daily point-of-sale reporting and updates) Disadvantages: - Coverage in remote areas can be a challenge (far from provider's antenna) - Speed limitations (although this might be changing. Some are suggesting this could replace wired ISP services)

Answer 120

Advantages: - Portability (Good for remote sites, difficult-to-network sites, RVs, etc.) - Always-on connection (as opposed to intermittent cellular) Disadvantages: - High cost relative to terrestrial networking - Speed not wonderful (50 Mbit/s down, 3 Mbit/s up are common) - High latency (Some of the best response times: 250 ms up, 250 ms down) [Remember Alaska phone call?] - Line of sight communication that requires nothing be between you and satellite ("Rain fade" - Rain clouds can interrupt connection)

Answer 121

T1s, T3s, and Optical Carriers (OCs) are point-to-point connections. Server providers still needed another level of devices in order to enable them to connect multiple T1s, T3s, and OC connections together in a mesh (i.e. to get data from one central office to another). To do this, they developed packet switching protocols that were functionally identical to routable network protocols like TCP/IP. Traditionally, two different forms of packet switching were Frame Relay (now a dying technology) and ATM (now a dead technology). [For more, See Meyers' AIO]

Answer 122

Frame Relay is an extremely efficient packet-switching standard, designed for and used primarily with T-carrier lines. Was one of the first cost-effective WAN types that became popular in the 1990s. Effectively replaced by MPLS and other tech, but still seen on legacy networks. Allows speeds from 64 kbps to 44-50 Mbps. Offered no data integrity. Discards frames when there's network congestion. But wasn't a huge problem because T-carrier lines have low error rates. Higher-level protocols needed to do the error-checking. [Don't let the term "packet-switching" confuse you. It operates at Layer 1 and 2 of OSI model, using frames rather than packets] [Compares with ATM and more recent MPLS]

Answer 123

Asynchronous Transfer Mode A once-popular WAN protocol (now dead) used over SONET networks. (OC lines usually connected to an ATM switch.) Integrated voice, video, data on one connection, using short, fixed-length, evenly-spaced 53-byte frames called cells. (Ethernet had to be split apart and placed in these cells, then reassembled on other side.) Offered high-throughput and low latency. Great for real-time communication. Speeds ranged from 155 to 622 Mbps, but Messer says highest OC got as high as 10 Gbps. (Bottom line: a lot faster than Frame Relay?] From Wiki: "ATM is a core protocol used in the SONET/SDH backbone of the public switched telephone network (PSTN) and in the Integrated Services Digital Network (ISDN), but has largely been superseded in favor of next-generation networks based on Internet Protocol (IP) technology, while wireless and mobile ATM never established a significant foothold." [ExamCram book says it uses to types of virtual circuits: PVC (permanent) and SVC (temporary). But isn't ATM packet switching?? Wow, apparently uses features of both packet and circuit switching] [Like Frame Relay, operates at Layer 2 of OSI model] [Compares with Frame Relay and MPLS. Like Frame Relay, ATM was effectively replaced by MPLS? Maybe just by IP networking technologies]

Answer 124

Apparently, it helped ATM handle the different transfer requirements of data v. audio/video. Data tolerates a delay in transfer, but not signal loss. And vice-versa for audio/video. By keeping frames small and evenly spaced, reduced jitter.

Answer 125

- Relatively slow at 44-50 Mbps - No data integrity - Allowed variable-length frames [inefficient?] - Insufficient for real-time uses like video and voice, etc [In part, I think, due to variable-length frames]

Answer 126

- ATM's tiny frames added quite a bit of overhead when breaking down and reassembling much larger ethernet frames - Complex mechanisms used to achieve QoS - Congestion may cause frame ("cell") loss - Expensive

Answer 127

Data Over Cable Service Interface Specification) A protocol used by cable modems [Yes, this question is out of order. Probably not even necessary]

Answer 128

Multiprotocol Label Switching (MPLS)

Answer 129

A WAN technology that improved upon ATM and Frame Relay, keeping their advantages while ditching the disadvantages. Directs traffic using short labels instead of long network addresses, avoiding complex, slow lookups in routing tables. Agnostic in terms of transport medium and protocols it carries. e.g. Allows IP packets, ATM cells, Ethernet frames. MPLS pushes labels onto packets as they enter into MPLS cloud, and pops them off on way out. Inside the MPLS cloud, you have Customer Edge Routers, Provider Edge Routers, Label Switch Routers. [Not clear if I need to understand all this] [I believe Network Chuck said he thinks MPLS is going away in favor of Software-Defined (SD) WAN]

Answer 130

Point-to-Point Protocol

Answer 131

A Layer 2 protocol used to establish a connection between two nodes. Works with plain old telephone service (POTS), mobile, ISDN, fiber links such as SONET, and other faster connections, such as T1. Provides data link functionality such as authentication (i.e. allows remote users to log on to the network and have access as though they were local users on the network), compression, error detection, and multilink, but does NOT provide data security / encryption. Multilink PPP: Building off of PPP, allows configuring multiple links to act as one, thus increasing connection speed. Has gained popularity with the cloud, but still suffers from problems inherent with PPP.

Answer 132

Point-to-Point Protocol over Ethernet

Answer 133

Offers the capability to encapsulate PPP frames inside Ethernet frames. First utilized to tunnel packets over a DSL connection to an ISP’s IP network. Although it has been around for many years, it is still widely used by DSL Internet providers. It is NOT used by cable (or fiber) Internet providers. Easy to implement. Supported in most operating systems. No routing required. Similar to existing dialup architecture. Allows competition (i.e. Allows choices in ISP). Once connected, data is switched to the appropriate ISP.

Answer 134

Dynamic Multipoint Virtual Private Network

Answer 135

A popular Cisco technology, offers capability to create a dynamic-mesh VPN network without having to preconfigure all possible tunnel endpoints. Tunnels are built dynamically, on-demand depending on which locations need to communicate. (e.g. a main office might want to connect with individual remote sites. Or perhaps some of the remote sites want to communicate with each other. Can dynamically build connection, communicate, and then tear down the connection. Allows most efficient possible communication.)

Answer 136

Session Initiation Protocol Trunking

Answer 137

A WAN technology in which SIP is used as a streaming media service with VoIP to provide telephone services and unified communications. It requires the use of SIP-based private branch exchanges (IP-PBX) and Unified Communications software applications, such as voice, video, and other streaming media applications (desktop sharing, shared whiteboard, web conferencing, and the like). More efficient use of bandwidth than traditional PBX connectivity using T1/ISDN. Can control how much compression you're using on these VoIP calls. Less expensive than ISDN lines. More phone system options [Don't really understand this too well. In terms of relationship to VoIP, one site says SIP is just one very common signaling protocol used to connect participants in a VoIP call. SIP requires VoIP, but not vice versa. Says that H.323 is one example of an alternative protocol?? Another site says SIP is a protocol used to initiate, maintain, and terminate multimedia sessions in VoIP applications.] [In terms of a trunk, the word comes from telecom world and it means, more or less, a group of phone lines. So basically, a SIP trunk is a set of virtual phone lines that enable users to make and receive phone calls. Someone says SIP trunk allows you to eliminate VoIP gateways. Phone calls come in via IP]

Answer 138

A demarcation point is the point where a service provider's equipment connects to your home or building. It distinguishes the ISP's area of responsibility from the customer's. It might be an interface location on the outside of the building, or inside. Just looks like a utility box. in a business, there's often a central location in the building for all demarcs from all providers. There's usually an interface device or "smartjack." Can be as simple as an RJ-45 connection. On customer side of demarc, you connect your CPE (i.e. Customer Premises Equipment or "customer prem").

Answer 139

Any wiring or cabling that connects the demarc to your Customer Premises Equipment (CPE). (A demarc may not always be in a convenient or functional place.)

Answer 140

network interface units (NIU) [smartjack?] network interface boxes (NIB) network interface devices (NID)

Answer 141

Demarc hardware that performs intelligent functions, such as: - Loopback feature (for remote troubleshooting) - Signal amplification (like a repeater on Ethernet network) - Surge protection - Remote alarm (if something goes wrong( [I think we've had smart jacks. Comcast box at Norchester had surge protection and battery backup and alarm, I believe] [Sounds like it may be used synonymously for demarc / NIU / NIB / NID. Or it might just be used for a demarc that possesses certain functionality. Not clear.]

Answer 142

Channel Service Unit / Data Service Unit

Answer 143

A channel service unit/data service unit (CSU/DSU) acts as a translator between the LAN data format and the WAN data format. Such a conversion is necessary because the technologies used on WAN links are different from those used on LANs. Some consider a CSU/DSU a type of digital modem. But unlike a normal modem, which changes the signal from digital to analog, a CSU/DSU changes the signal from one digital format to another. Traditionally, the CSU/DSU has been in a box separate from other networking equipment. However, the increasing use of WAN links means that some router manufacturers are now including CSU/DSU functionality in routers. The CSU connects to the network provider (often using RJ-45). DSU connects to data terminal equipment (DTE) (e.g. commonly a router) often using a serail connection.