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109 Cards in this Set
- Front
- Back
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What is the OSI Model?
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Describes the data communication processes; consists of 7 layers.
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What are the 7 layers of the OSI model?
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7- Application
6- Presentation 5- Session 4- Transport 3- Network 2- Data Link 1- Physical |
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According to the OSI model, how does information flow?
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Information flows from Layer 7, the application layer, to Layer 1, where it's placed on the physical network circuits. After it arrives at the next device, it will flow up and down the layers as needed.
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What Layer of the OSI model do data switches typically look at to make switching decisions?
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Data switches typically only look at information at layer 2.
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What layer, on the OSI model, do routers look at?
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Layer 3
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What layers do clients and servers use on the OSI model?
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Clients and servers make use of all seven layers.
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What does OSI stand for?
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Open Systems Interconnection
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What does the OSI model help you do?
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It helps you verify the success of the communication process at various layers or levels of the model; it also helps you locate the point of failure.
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What is the focus of Layers 1 and 2 of the OSI model?
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Communication over the "wire"
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What are 5 ways you can troubleshoot OSI layers 1 and 2?
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1- View the contents of your ARP cache
2- NETSTAT- program that can be used to determine local area network physical connectivity 3- Protocol Analyzer- used to diagnose a physical network problem 4- Link status and activity counters 5- Link Lights |
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Using netstat -e, how would you know that you're having a problem with your Ethernet activity?
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When you netstat -e, wait a few minutes and do it again, you should see a change in the number. If you do, you are communicating.
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What's the only issue with ARP?
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The ARP cache is often empty because old entries disappear on a regular schedule.
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What is ARP?
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ARP is a process used to locate other devices on your local network to get their Media Access Control (MAC) address. If you have entries in your ARP cache, you are communicating with other devices.
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When checking link status for a router or a switch, how would you know if there's a problem?
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would say 'Ethernet 0/0 is down, line protocol is down.'
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If you don't have any problems at Layers 1 and 2, what should you do?
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start looking for the problem at layer 3.
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When troubleshooting Layer 3, what do you need to determine?
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You need to determine if your address is correct and that the network will actually route your traffic to other devices.
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What are 6 ways to troubleshoot OSI layer 3?
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1- IPCONFIG
2- Ping 3- Tracert/Traceroute 4- Pathping 5- Internet Communications MNGT Protocol (ICMP) Messaging 6- Protocol Analyzer |
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What's the first step in troubleshooting OSI Layer 3?
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Making sure we have proper addresses on a windows device through IPCONFIG.
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What does IPCONFIG show?
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Shows the IP address, mask, and default gateway info that is currently in use on the device
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What does ipconfig/all show?
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shows all the configuration details- address of the DNS server, the DHCP server if used, the DNS domain info, etc.
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Under ipconfig/all, what do you need to verify?
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that the IP address, the subnet mask, the default gateway, and the DNS server address are correct for the subnet in which you are located.
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What does ping test?
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your connectivity in the network
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You can ping by...
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IP address or domain name
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Why would you ping other workstations on your local network?
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to see if there's a local connectivity problem.
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What does it mean if you can't ping your default gateway?
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you don't have connectivity to the router and won't be able to access any devices that aren't on your LAN.
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What is tracert?
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a command used to display the addresses of the routers used to go between your device and the device you wish to trace the route to.
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What is Pathping?
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does the same initial process as tracert but then goes on to calculate more precise network times for each "hop" in the route
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What's the difference between using tracert and pathping?
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Tracert gives you results in a hurry; if you have more time and need more detailed throughput numbers, pathping might be more useful.
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What is ICMP?
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Internet Communications Management Protocol (ICMP); provides details as to why a communication pathway is not available.
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What does the transport layer (OSI 4) deal with?
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moving information between client and server applications; you'll need to know what applications are available.
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What is telnet?
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Application program that was designed for terminal emulation.
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What is the telnet command?
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tenlet serverIP Port#
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What are 3 ways to troubleshoot OSI layer 4?
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1) Telnet
2) Port scanning 3) Protocol Analyzer |
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What does a Port Scanner do?
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sends probing messages to the server in question and sees if the server responds; shows what applications are available on the server
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What does Protocol Analyzer show you for OSI layer 4?
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Shows each element of the datagram and each part of the associated protocols.
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What does Layer 7 of the OSI model do?
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Provides services for user applications to employ; defines the interfaces for communication and data transfer; provides and support services such as job transfer, handles network access, email, supports user apps and error recovery.
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Define HTTP.
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Hypertext Transfer Protocol- protocol that operates at the application layer
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What are the protocols on Layer 7 and what do they do?
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FTP, DNS, SNMP, SMTP, FINGER, TELNET, TFTP, BOOTP, and SMB; enables various functions at this layer.
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What is Layer 6 responsible for?
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The presentation layer translates the data from application to the network format; responsible for the protocol conversion, encryption, decryption, and data compression; is a best layer for cryptography.
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What network device operates on Layer 6?
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gateway network device
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What is Layer 5 responsible for?
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Session Layer- establishes and manages the session between the 2 users at difft ends in a network; manages who can transfer the data in a certain amount of time and for how long; reports and logs any upper layer errors.
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What protocols work on Layer 5?
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NetBIOS, Mail Slots, Names Pipes, RPC
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What network device is used in Layer 5?
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Gateway
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What is Layer 4 responsible for?
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Transport Layer: manages end-to-end message delivery in a network and provides the error checking and hence guarantees that no duplication or errors are occurring in the data transfers across the network.
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What protocols work on Layer 4?
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TCP, SPX, NetBIOS, ATP, and NWLINK
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What network devices are used on Layer 4?
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Brouter, Gateway, and Cable Tester
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What is Layer 3 responsible for?
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Network Layer: determines how data transmits between the network devices; translates the logical address into the physical address, e.g. computer name into MAC address; defines the route, manages the network problems and addressing; routes the packets according to hte unique network addresses; router works as the post office and network layer stamps the letter (data)
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What protocols work on Layer 3?
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IP, ICMP, ARP, RIP, OSI, IPX, and OSPF
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What network devices are used on Layer 3?
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Router, Brouter, Frame Relay device, and ATM switch devices
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What is Layer 2 responsible for?
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Data Link Layer- define procedures for operating the communication links, frames packets, detects and corrects packets, transmits errors.
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What protocols work on Layer 2?
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Logical Link Control, Error Correction and Flow Control, Media Access Control
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What network devices are used on Layer 2?
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Bridge Switch, ISDN Router, Intelligent Hub, NIC, Advanced Cable Tester
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What is Layer 1 responsible for?
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Physical Layer: defines cables, network cards, and physical aspects; defines raw bit stream on the physical media; provides the interface b/w network and network communication devices; checks the # of bits transmitted per second and 2 way or 1 way transmission.
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What protocols work on Layer 1?
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ISDN, IEEE 802 and IEEE 802.2
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What network devices are used on Layer 1?
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Hubs, Repeaters, Oscilloscope, and Amplifier
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What are the different types of networks?
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1) Peer to Peer
2) Client/Server 3) Centralized |
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What is a peer-to-peer network?
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A network that lacks a dedicated server; every computer acts as both a client and a server; good solution when there are 10 or less users that are in close proximity to each other; can be a security nightmare
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What is a client/server network?
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a network that's designed to support a large number of users and uses dedicated server(s) to accomplish this; clients log into the server in order to run applications or obtain files; can be managed by one or more administrators.
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What is a centralized server?
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a client/server based model that is most often seen in UNIX environments but the clients are "dumb terminals"; security is very high.
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Define the 6 network topologies.
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1) Bus
2) Star 3) Ring 4) Hybrid 5) Mesh 6) Wireless |
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Describe the Bus Network topology.
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Each of the computers on the network are daisy-chained to each other; creates excess traffic, must pass information from one to the other.
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What are the advantages and disadvantages of the Bus network topology?
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Advantages: cheap, simple to set up
Disadvantages: excess network traffic, a failure may affect many users, problems are difficult to troubleshoot. |
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Describe the Star Network Topology.
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Uses twisted pair (10baseT or 100baseT) cabling and requiring that all devices are connected to a hub.
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What are the advantages/disadvantagees of the Star Network Topology?
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Advantages: centralized monitoring, failures do not affect others unless it is the hub, easy to modify; Disadvantages- if the hub fails, then everything connected to it is down.
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Describe the Ring Network Topology.
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Looks the same as the Star, except it uses special hubs and ethernet adapters.
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What are the advantages/disadvantages of the Ring Topology?
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Advantages: equal access
Disadvantages: Difficult to troubleshoot, network changes affect many users, failures affect many users. |
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Describe the Hybrid Network Topology.
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Combinations of the Bus, Star and Ring and are common on very large networks.
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Describe the Mesh Network Topology.
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Every node has a connection to every other node in the network.
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What are the advantages and disadvantages fo the Mesh Network?
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Advantage: Provides redundancy in case of a failure b/w links
Disadvantage: Can be very expensive. |
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Describe the Wireless Network Topology.
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allow computers to communicate without the use of cables; IEEE 802.11b defines 2 pieces of equipment, a wireless station, which is usually a PC or a laptop with a wireless network interface card (NIC), and an Access Point (AP), which acts as a bridge b/w the wireless station and Distribution System (DS) or wired network.
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Describe the modes an 802.11b wireless network adapter can operate in.
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2 modes: 1) Ad Hoc, 2) Infrastructure. Infrastructure mode: all traffic passes through a wireless access point; Ad-Hoc mode: Computers talk directly to each other and do not need an access point at all.
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What are the advantages and disadvantages of the Wireless Network Topology?
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Advantage: world-wide acceptance, rnages over 150 feet, freedom to move about and no cables; Disadvantages: Susceptible to interference form objects such as microwave ovens and cordless phones.
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What is the Standard, Cable Type, Connect, Max. Length, and Speed of the 10 Base-T cable?
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Standard: 802.3i, Cable Type: Category 3 or better UTP cable, Connector: RJ-45, Max. Length: 100 meters (328 ft), Speed: 10 mbps
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What is the Standard, Cable Type, Connector, Max. Length, and Speed of the 10Base-FL cable?
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Standard: 802.3j, Cable Type: Fiber Optic cable, Connector: ST, Max. Length: 2000 meters, Speed: 10 mbps
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What is the Standard, Cable Type, Connector, Max. Length, and Speed of the 100 Base-TX cable?
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Standard: 802.3u, Cable Type: Cat 5 twistered pair, Connector: RJ-45, Max. Length: 100 meters (328 ft), Speed: 100 mpbs
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What is the Standard, Cable Type, Connector, Max. Length, and Speed of the 100Base-FX cable?
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Standard: 802.3u, Cable Type: Fiber Optic, Connector: ST, SC, Max. Length: 2000 meters, Speed: 100 mbps
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What is the Standard, Cable Type, Connector, Max. Length, and Speed of the 1000Base-T cable?
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Standard: 802.3ab, Cable Type: CAT5e or higher, Connector: RJ-45, Max. Length: 100 meters (328 ft), Speed: 1 gbps
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What is the Standard, Cable Type, Connector, Max. Length, and Speed of the 1000 Base-LX cable?
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Standard: 802.3z, Cable Type: Laser over fiber, Connector: SC, Max. Length: Up to 5,000 meters, Speed: 1 gbps
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What is the Standard, Cable Type, Connector, Max. Length, and Speed of the 1000Base-SX cable?
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Standard: 802.3z, Cable Type: short wavelength laser over fiber, Connector: SC, Max. Length: Up to 550 meters, Speed: 1 gbps
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What is the Standard Cable Type, Connector, Max. Length and Speed of the 1000 BASE-CX cable?
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Standard: 802.3z, Cable Type: Twinax or short haul copper, Connector: 9-Pin Shileded D-subminiature connector, or 8-pin ANSI fiber channel type 2 (HSSC) connector, Max Length: 25 meters, Speed: 1 gbps
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What is the Standard, Cable Type, Connector, Max. Length, and Speed of the 10 GBASE-LR cable?
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Standard: ?, Cable Type: Laser over single mode fiber optics, Connector: ?, Max Length: 2000 meters, Speed: 10 Gbps
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What is the Standard, Cable Type, Connector, Max. Length, and Speed of the 10 GBASE-SR cable?
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Standard: 802.3ae, Cable Type: short wave laser over multi-mode fiber optics, Connector: ?, Max. Length: 300 meters, Speed: 10 Gbps
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What is the Standard, Cable Type, Connector, Max. Length, and Speed of the 10GBASE-ER cable?
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Standard: ?, Cable Type: Laser over eithe rsingle or multi-mode fiber, Connector: ?, Max. Length: 40,000 meters, Speed: 10 Gbps
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What's the difference between a shielded twisted pair (STP) and a UTP?
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a shielded twisted pair (STP) has a foil jacket that helps preent crosstalk.
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Define crosstalk.
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Crosstalk is signal overflow from an adjacent wire.
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What is the 5-4-3 rule?
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States that a 10base 2 network can have 5 cable segments connected with 4 repeaters, but only 3 of these segments can be occupied by computers; there's a max. of 30 computers per segment.
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Describe plenum grade cabling.
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Plenum grade cabling is required if the cabling will be run between the ceiling and the next floor (pleum), resistant to fire and does not emit poisionous gasses when burned.
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Describe the security in fiber optic cabling.
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Has a built-in security as you can't intercept data as you can with other cable mediums.
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What is the frequency, description, Max. Length, and speed of the 802.11b WiFi wireless technology?
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Frequency: 2.4 Ghz, Description: wireless networking commonly used in homes and SOHO environments, uses a wireless access point (WAP) to connect to other wireless computers, Speed: 11 mbps
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What is the frequency, description, Max. Length, and speed of the 802.11g WiFi wireless technology?
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Frequency: 2.4 GHz, Description: commonly used in homes and SOHO environemnts, uses a wireless access point (WAP) to connect to other wireless computers; backward compatible with 802.11b, Max. Length: 150+ feet, Speed: 54 mpbs
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What is the frequency, description, Max. Length, and speed of the Infrared- IrDA wireless technology?
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Frequency: uses light, not radio frequencies, Description: uses line of signt connections making it useful for sharing data between personal devices, Max. Length: 150+ feet, Speed: usually 16 mpbs- high powered beams can reach 10 Gbps
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What is the frequency, description, Max. Length, and speed of the Bluetooth wireless technology?
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Frequency: 2.4 GHz, Descrption: is a specification for wireless personal area networks that facilitates the exchange of data between electronic devices.
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Define infrared-IrDA.
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A short range line of sight technology which means that there cannot be obstructions between 2 devices that are trying to communicate.
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Why was bluetooth developed?
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Out of a demand to create networks that were easy to install, configure and use without using the standard cabling.
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Fill in the blank: The higher the network device is in the OSI layer, ________________
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the more intelligent the device is.
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What is NIC?
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Network Interface Card (NIC): an expansion board you insert into a computer so the computer can be connected to a network.
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How are NICs designed?
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Most NICs are designed for a particular type of network, protocol and media.
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What is a hub?
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used to connect computers on an ethernet network.
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What is a repeater?
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boosts signals in order to allow a signal to travel farther and prevent attentuation; repeaters do not filter packets and will forward broadcasts; cannot connect unlike network segments.
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Define attentuation.
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the degradation of a signal as it travels farther from its origination.
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What is a bridge?
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Functions the same as a repeater, but can also divide a network in order to reduce traffic problems; can also connect unlike network segments; create routing tables based ont he source address.
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Identify 3 bridging methods.
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1) Transparent- only one bridge is used; 2) Source Route- bridging address tables are stored on each PC on the network, 3) Spanning Tree- prevents looping where there exists more than one path b/w segments.
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What is a switch?
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prevents traffic jams by ensuring that data goes straight from its origin to its proper destination, w/ no wandering in b/w. Switches remember the address of every node on the network & anticipate where data needs to go; only operates w/ computers on the same LAN.
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What is a router?
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similar to a switch but can also connect difft logical networks or subnets and enable traffic that is destined for networks on the other side of the router to pass through; can connect networks that use dissimilar protocols.
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What is a gateway?
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Used as a connection to a mainframe or the internet; enable communications b/w difft protocols, data types and environments.
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What is a file server?
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a very fast computer with a large amount of RAM and storage space, along with a fast NIC (Network Interface Card).
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What does a file server do?
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controls the communication of information between the nodes on a network; stores alot of information and shares it very quickly.
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What are the minimum requirements for a file server?
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- 800 MHz or faster processor
- fast HD with at least 120 gb - a RAID (Redundant Array of Inexpensive Disks) to preserver data after a disk casualty - a tape back up unit (DAT, JAZ, Zip,or CD-RW d\rive) - numerous expansion slots - fast NIC - at least 512 MB of RAM |
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What is a NIC?
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Network Interface Card- provides the physical connection between the network and the computer workstation; most are internal and determine the speed and performance of a network.
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