|
Papers > Technology > network
Featured Papers from Direct Essays |
|||
1. What is a computer network
|
|||
This is a preview of a paper to view the full text you need to signup and login.
network |
|||
|
... 1 Recognize the following logical or physical network topologies given a schematic diagram or description: • Star/hierarchical • Bus • Mesh • Ring • Wireless Star/Hierarchical A star physical topology usually doesn’t look like a star, except on paper. The mark of this topology is what you’ll find at the center, namely a centralized hub or switch to which are connected all the network’s nodes/devices. ... • Network growth is easily accommodated. CONS: • All nodes on the network receive the same signal, dividing the bandwidth. • Maximum number of computers is 1,024 on a Local Area Network (LAN). ... Bus A bus physical topology means that all of the devices on the network are connected to a common backbone. ... (Just try and locate a break in the cable, or the device causing the fault when the entire network is down. ... Mesh In a mesh physical topology, every device on the network is connected to every other device on the network. This topology is most commonly used in Wide Area Network (WAN) configurations PROS: • Provides redundancy and it’s always easy to find a quick route through the network. ... Ring In a ring physical topology, the devices on the network are wired into a conceptual circle. ... CONS: • Difficult to locate the problem cable in a network segment and hardware is expensive. Wireless As the name implies, a wireless network topology is made up of nodes that communicate without physical data transmission media; in other words, no wires. ... PROS: • With wireless connectivity, computers have freedom of mobility while remaining continuously connected to network. ... Here are a few other online resources on network topologies: Webopedia’s take on Network Topologies (does not include Wireless) Webopedia’s take on Wireless Network Computing Home and Small Office Network Topologies, a’la Microsoft Wireless Success Stories Controlling Microwave Links in Wireless Networks Dawn of a New Database The Wireless LANs Page Introduction to WLAN Topology Otterbein Lecture on Network Topologies 1. ... *” refers to the set of network standards developed by the Institute of Electrical and Electronic Engineers (IEEE). ... 6 Metropolitan Area Network (MAN) 802. ... The MAC layer, which varies for different network types, is itself defined by standards IEEE 802. ... The LLC sublayer provides the interface between the MAC sublayer and the Network Layer above the Data Link Layer. ... 3 standard specifies any network that uses baseband signaling and a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) signaling method. ... With CSMA/CD, a computer will “listen” to the network to be sure the way is clear for it to send its data. ... The computers on the same network competing for the same network media is the “Media Access”. ... Transmission speed on a token ring network often will be determined by the slowest Network Interface Card (NIC) present. ... Unlike Ethernet, a computer cannot talk on the network unless it has the token (compare that with CSMA/CD discussed above). ... The other standards referenced in CompTIA’s Network+ test objectives break down like this: Standard Speed Access Method Topology Types Cable Types 802. ... 11b to the test Dan Bricklin’s Home Network: Wireless 802. ... Here are other network cabling resources available on the web: An Excellent Gigabit Ethernet Page Webopedia’s list of cables and networking hardware A How-to Cable Web page Ethernet Cables and Accessories This is a commercial site with lots of great cable pictures Very, very good pictures of Ethernet cable and network implementation A Couple of Fiber Optic Tranceivers And, uh, not to scare anyone – it’s not likely to turn up on the test – but here’s a White Paper on 10GB Ethernet and 10 Gigabit Ethernet Alliance Home Page 1. ... Its possible to find RJ-11 connectors linking network nodes in certain types of LANs, though RJ-45 connectors are far more common. ... If your computer is attached to a standard Ethernet network, pull out the cable and have a look. ... You’ll find them most often on 10base2 thinnet and ARCnet networks, but they can be used on any network that uses coaxial cable. ... It attaches to a T-connector which in turn attaches to a network interface card. ... SC connectors work with single-mode or multimode optical fibers and will last for around 1,000 “matings” (well, you knew network management could be exciting). ... 5 Choose the appropriate media type and connectors to add a client to an existing network. ... 6 Identify the purpose, features, and functions of the following network components: • Hubs • Switches • Bridges • Routers • Gateways • CSU/DSU • Network Interface Cards/ISDN adapters/system area network cards • Wireless access points • Modems Hubs A hub is a device that connects together all the segments of a single network. ... Like Network Interface Cards (see below), hubs come in both standard (10 Mbps) and Fast Ethernet (100 Mbps) versions. Also, generally speaking, if your network is small, say less than 10 devices in a peer-to-peer, then a hub may be all you need. ... By contrast, active hubs do regenerate and process signals, much as does a device not mentioned on CompTIA’s Network+ objectives, a repeater. ... This device physically connects network computers in a physical star topology with a logical ring structure. ... Advice on Choosing a Hub Lyksinks Examples of Hubs How to Setup a Peer-to-Peer Network Without a Hub Switches Switches do have a thing or two in common with hubs. Both devices connect multiple segments of a single network and both allow those devices to talk to each other. ... Compare that to a hub, which rebroadcasts signals out from all ports, so all the devices on the network will see the signal. On a switched network, only the sending device and the receiving device see the signal. ... What you have is a device that acts like a switch but uses IP or network addresses, which are Layer 3. ... Difference Between a Hub and a Switch Bridges Bridges provide an inexpensive and easy way to connect network segments, much as hubs and switches do. Like switches, they connect two segments on a network. ... So think of a switch as designed to communicate with individual nodes while a bridge communicates with and between network segments. ... When designing a network with more than one segment, the debate often comes down to whether to use a bridge or a switch or to opt for a router. ... This is especially helpful in creating larger networks, and to keep network segments free of data that doesnt belong in a particular segment. Click Here to View a Good Diagram of a Bridged Network HomeNetHelp Bridge Tutorial Routers A router, which operates at Layer 3 of the OSI Model, can create and connect several logical networks. However—and here’s the key difference between a router and a bridge or a switch—a router also will allow two different network topologies, such as Ethernet and Token Ring, to connect into a single network. ... Routing over a segmented network is no different than routing over an internetwork. ... When you’re thinking about hubs, bridges, switches and routers, remember that routers are the only devices of the four that will allow you to share a single IP address among multiple network clients. ... In other words, it’s a network point where one network can enter another (like a “gate,” get it? ... These systems are the most complex of all the network devices CompTIA expects you to know about because they translate at multiple layers of the OSI Reference Model. ... Gateways exist on the borders of a network, which means they are functionally related to firewalls. Channel Service Unit/Data Service Unit (CSU/DSU) Short for Channel Service Unit/Data Service Unit, the CSU/DSU is a common device found in equipment rooms where the network is connect via T-series data connectors (in other words, like a T1 or T3). The CSU/DSU connects a digital carrier (such as the T1) to the network equipment (usually a router). ... CSU/DSU A’La Alliance Datacom GDC White Paper: CSU/DSU Non-integrated vs Router-integrated Network Interface Cards/ISDN Adapters/System Area Network Cards A NIC is everything its name suggests. It’s a “card” inserted into a networked device that is used to create an interface with that network. Look on the back of your computer and find where the RJ-45 (or whatever media your network uses) is plugged into your computer. ... For instance, a PCMCIA network adapter will connect a laptop to a network through the credit card-sized PCMCIA expansion slot. A pocket adapter will connect a PC to a network through its printer port. How to Install a NIC Wireless Access Points As the name suggests, wireless access points transmit network signals to wireless client devices. ... To do this, you must use a wireless bridge, which takes you beyond the scope of the Network+ exam. ... OSI Model Layer Layer Name Header Protocols & Services Details 7 Application (All) Protocol Data Unit Telnet, FTP, SMTP, HTTP, File and Print, E mail, (WWW), EDI, SMB, NCP User requests network services here. ... 3 Network (Need) Datagrams or Packets IP, IPX, RARP, ARP, BootP, DHCP, ICMP, BGP, OSPF, RIP. ... Decides how data will be routed across the network, in addition to the structure and use of logical (IP) addressing. ... The electrical and physical specifications for the network media that carry data bits across a network. ... 3 Differentiate between the following network protocols in terms of routing, addressing schemes, interoperability, and naming conventions: • TCP/IP • IPX/SPX • NetBEUI • AppleTalk TCP/IP • Routing Uses IP address of the sender, the recipient and the next router to determine path. ... • Addressing IP or network addressing. ... The protocol is turning up more and more in non-traditional network settings, such as vending machines and household systems. ... • Addressing Uses each node’s 12-digit hexadecimal address as it exists on a given segment, which will itself be represented by its own unique 8-digit hexadecimal IPX network address. ... • Naming There is very, very little network addressing in NetBEUI/NetBIOS. ... • Addressing Uses a 24-bit address, of which 16 bits are allotted to the network. Each network segment will receive either one 16-bit network number (supports up to 254 nodes per network) or a range of 16-bit numbers (called “extended AppleTalk” because it can support more than 254 nodes). ... AppleTalk networks also use areas called zones, which allow a network to be segmented into logical areas. ... • Naming Uses Name Binding Protocol (NBP), which associates a computer’s node name with its network address. This protocol is broadcast-based, so every device broadcasts its name when it logs onto the network. ... 4 Identify the OSI layers at which the following network components operate: • Hubs • Switches • Bridges • Routers • Network Interface Cards Device OSI Model Layer Hubs Layer 1 (Physical) Switches Layer 2 (Data Link) Bridges Layer 2 (Data Link) Routers Layer 3 (Network) Network Interface Cards Layer 1 (Physical) Please note: the above doesn’t tell the whole story. ... It provides the basic delivery mechanism for all packets sent between all systems on a network or on the Internet. ... All hosts on a network have a logical, Layer 3 IP address. An IP address designates the location of a device on the network, and information can be routed via those addresses. ... UDP is a stream-lined, economy class version of TCP, earning it the nickname “thin protocol,” which means it doesn’t take up much bandwidth on the network. ... UDP doesn’t offer the assurances of TCP, but does a very good job of getting data from one host to another using fewer network resources to do so. ... HTTPS allows browsers and servers to sign, authenticate and encrypt an HTTP network packet. ... Telnet “Telnet” stands for “Telephone Network,” so called because most Telnet sessions occur over a telephone network. ... Once the connection is established, the computer acts as if on the network. ... ICMP (Internet Control Message Protocol) ICMP works with IP at Layer 3 of the OSI Reference Model to provide Network Layer management and control. ... ICMP will provide feedback about problems you may be experiencing on your network, but it won’t make IP any more reliable than it is (which isn’t much). ... ARP (Address Resolution Protocol) Address Resolution Protocol resolves network (IP) addresses to hardware (MAC) addresses. ... This table maps IP addresses to MAC addresses on the network. ... Click here for a more in depth article on ARP Address Resolution Protocol Spoofing and Man-in-the-Middle Attacks Click here to read about RARP (Reverse Address Resolution Protocol) NTP (Network Time Protocol) NTP sets computer clocks to a standard time source, usually a nuclear clock. This is what keeps all computers on a network set to the same time, which is important for transactions that need time and date stamping. ... Port numbers keep track of data communication as it streaks across a network. Some of the better known port numbers are: Port Number Utility Used by Function 15 NETSTAT UDP Network Status 20 FTP (data transfer) TCP, UDP File Transfer Protocol for Data 21 FTP (control) TCP, UDP File Transfer Protocol for control 23 Telnet TCP, UDP Connects a remote computer to a server 25 SMTP TCP, UDP Delivers email between email hosts 53 DNS UDP Translates host names to IP addresses 69 TFTP UDP Trivial File Transfer Protocol 80 HTTP TCP, UDP Opens a browser connection to a website 110 POP3 TCP, UDP Delivers mail between mail host and client 161 SNMP UDP Monitors the network and network devices For a full listing of port numbers, click here. ... Subnetting is taking a single network IP address and subdividing it, thus creating more subnets and allowing your network to grow. ... The difference between a public and private network: A public network sits in front of a firewall, and does not enjoy its protection. A private network sits behind the firewall, and does. So, you need to be sure to install your firewall on the outer edge of the network to make as much of it private as possible. A firewall is what keeps intruders (hackers, clumsy surfers, corporate spies, etc) out of your network. Just as a real firewall will protect one side of a building from fire on the other sides, a network firewall acts as a barrier to network traffic on one side to protect the network on the other. To understand this concept, it is most helpful to realize that your network is part of the larger Internetwork. ... Your “private” network sits behind the firewall, which helps keep your little part of the Internet “private.” A firewall can be configured with rules to control which packets will be accepted into the private network, and which can pass out of it. ... In circuit-switched networks, network resources are static (“set in copper” if you will) from the sender to receiver before the start and until the end of the transfer, thus creating a logical “circuit”. In packet-switched networks, the message is broken into packets, each of which can take a different route through the network to the destination where the packets are reassembled into the original message. So, in packet-switched networks, resources are not reserved and a sessions messages may have to wait for network resources. ... When sending short messages, the setup delay easily can make up a large proportion of the total connection time, which means a reduction in network capacity. ... com on circuit and packet switching Bell Labs Technology: Understand Digital Circuit Switching ISDN (Integrated Services Digital Network) ISDN is a digital telecommunications network which carries voice, data, and video over existing telephone network. ... So the first phrases you should learn about ISDN are: • POTS – Plain Old Telephone Service • PSTN – Public Switched Telephone Network POTS and PSTN are one and the same. ... It’s used primarily for communication, or "signaling," between switching equipment in the ISDN network and the onsite ISDN equipment. ... ISDN devices include terminals, terminal adapters (TAs), network-termination devices, line-termination equipment and exchange-termination equipment: ISDN Device Type Description TE1 (Terminal Equipment type 1) Understands ISDN standards and can connect directly into an ISDN network TE2 (Terminal Equipment type 2) Predates ISDN standards; requires a terminal adapter (TA) to connect to an ISDN network. NT1 (Network Termination 1) Connects user devices to the ISDN network. NT2 (Network Termination 2) Usually a provider’s equipment, such as a switch or PBX. ... TA (Terminal Adapter) Converts TE2 wiring to TE1 to then connect into an NT1 device for conversion into a two-wire ISDN network. ... • U — The reference point between NT1 devices and line-termination equipment in the carrier network. ... And here are some other ISDN resources available online: ISDN: The “Obsolete” Dial-up Service That Won’t Go Away DSL vs ISDN Dan Kegel’s ISDN Page ISDN Tutorial ISDN Zone ISDN Council FDDI (Fiber Distributed Data Interface) FDDI is a Fiber LAN network standard composed of two counter-rotating rings, which is how it differs from Token Ring, as described in topologies above. ... An unbroken FDDI network can run to 100km with nodes being up to 2km apart on multi-mode fiber, and 10km apart on single-mode fibre. ... The maximum packet size on an FDDI network is 4. ... (If FDDI passes through a gateway to join with an Ethernet network, the FDDI packets must be broken up into smaller packets and given new headers.) When an FDDI network is functioning properly, data will move counter-clockwise on the primary ring. ... Nodes on a FDDI network are either Dual-Attached Stations (DAS) or Single-Attached Stations (SAS). ... ” • Media Access Control (MAC) - manages data transfers, error recovery, network addressing, token passing, and station access. ... ” On an FDDI network, data does not bypass other nodes on the ring. ... Each switch in a frame relay network relays the data (frame) to the next switch. ... If traffic on the network is light at any given moment, Frame Relay will start at the CIR but can reach speeds as high as 1. ... com’s Frame Relay page AllianceDatacom’s Frame Relay Tutorial Sonet/SDH In the United States, the standard for ATM on optical media is SONET (Synchronous Optical Network). ... This system was the first successfully to support DS-1 formatted digitized voice transmission that connected directly to a network. ... 12 Define the function of the following remote access protocols and services: • RAS • PPP • PPTP • ICA Protocol or Service Function RAS (Remote Access Server) A computer with one or more modems installed to facilitate remote connections to a network. ... PPTP (Point-to-Point Tunneling Protocol) Allows the creation of a Virtual Private Network, which gives users a secure, direct connection to a server or corporate network via the Internet. ... It operates at Layer 3 (Network) of the OSI Reference Model (see above) and secures all applications that operate at the upper layers (Transport to Application). ... L2TP’s main components are the L2TP Access Concentrator (LAC) and L2TP Network Server (LNS). ... L2TP uses packet-switched network connections. ... It is service-independent and can secure many different network applications. ... IPlanet’s SSL page How SSL Works Kerberos Kerberos is more than a network authentication protocol. ... 0 Network Implementation – 23% 3. ... Network+ contains questions relevant to each of these operating systems: Windows 2000 Pro Windows NT NetWare 5. ... A "client" is a node on a network that communicates with a server, which means it is part of a Client/Server network. ... Sites generally implement Client/Server networks when the number of devices on the network surpasses the 10- to 15-device recommended maximum of the peer-to-peer network . In addition to offering only limited resources for managing a network, peer-to-peer offers NO user-level security . The share-level security it does offer is often not adequate over the network, and non-existent at the local machine itself. ... A client-server network provides more flexibility than a peer-to-peer network: • It is more scalable. ... 3 Identify the main characteristics of VLANs VLANs (Virtual Local Area Networks) are groups of network nodes that form a single broadcast domain based upon logical associations rather than physical connections or location. ... For the exception, click here to read about one network’s “router-on-a-stick” design. ... • Reduced administration costs - VLANs provide an effective mechanism to control changes, such as physical movement of users within a network, and reduce hub and router configuration costs. VLAN users share network address space, no matter where they are physically. If a group of users moves physically but their group remains in the same VLAN connected to a switch port, their network address will not change. ... • Improved network security - By restricting users to their VLAN, you limit their ability to see other devices on the network. VLANs also can be used to provide security firewalls, restrict individual user access, flag any unwanted intrusion into the network, and control the size and composition of the broadcast domain. ... Once you’ve applied all that, your VLAN is set up and any network segments connected to the assigned ports will be part of that VLAN. ... If VLANs could communicate with each other on the same switch, it would defeat the purpose of having a VLAN, which is to isolate a part of the network. ... 4 Identify the main characteristics of network attached storage. Network attached storage is what many network administrators are using to replace file servers. File servers, which store files and make those files available to client users, are often the most frequently accessed servers on a network. ... Network Attached Storage units are smaller network devices (sometimes called “black boxes”), with a NIC, a large hard disk drive, and not much else. ... Aside from these odd (compared to traditional) characteristics, a Network Attached Storage device is otherwise just a file server. What it is, by comparison (and this is always attractive to bottomline- obsessed network administrators bosses), is cheap. A decent file server (say a Pentium II with 256 MB RAM and a multiple hot-swap HDD array) could run several thousand but a 20GB Network Attached Storage device may cost only a few hundred. ... It also takes only minutes to set up a Network Attached Storage device, compared to the several hours it takes for issuefree server installation (and you know there are ALWAYS issues). Steps to Install a Network Attached Storage Device 1. ... Plug in the network cable. ... IBM’s Network Attached Storage Devices Iomega’s Network Attached Storage Devices Kintronics Network Attached Storage Overview 3. ... A Fault-Tolerant network is, simply, one that can withstand, survive, and recover from errors. ... The first line of defense against any kind of errors—improving the network’s fault tolerance—is some form of data backup. ... RAID is only part of a network’s fault tolerance. ... Your network’s ability to recover from disasters is an important part of its fault tolerance plan. ... How a network administrator will cope with inevitable disasters will depend on the type of disaster and the amount of extant pre-planning for disaster recovery. ... • Fail Over – When one device, database, server, or network fails, a standby automatically takes its place. ... • Clustering A combination of hardware and software solutions used to produce a group of redundant, mirrored servers in a network that will take over quickly if the primary device fails or is shut down. ... (Note: On the Network+ exam, if something, anything, is not a good practice, then it’s a wrong answer.) • High Availability This the percentage of time over the period of a year that a network is available, or falls within an acceptable range (otherwise the availability would not be high). ... For the hows and whys on the distribution of resources on a network, click here. UPS (Uninterruptible Power Supply) Nothing on a network will work without electricity. The sudden removal of electricity not only keeps the network from functioning, but also can cause a great deal of damage to hardware and software. ... A UPS is a device that keeps the electrical flow to the network device steady, free of spikes and surges, for a short time when primary electrical power is lost. ... The switch to battery power as soon as the UPS detects a loss of primary power gives you time to save any work you’re doing and gracefully shut down the device, such as a network server. ... The SPS can take several milliseconds, during which time the network device will receive no power. ... • Travan – An enhancement of QIC, newer network storage versions hold up to 10 GB of compressed data. ... Hot and Cold Sites Hot Site – The primary operation site; this is where the network actually exists, on a daily basis. ... Planning for Redundancy When setting up your network with an eye towards redundancy, there are many key areas to consider, whether everyday components, spare parts on hand, or fault-tolerant technology: • Hard drives • Power supplies • Cooling fans • NICs • Multiple processors • UPSs • Backup generators • Cluster servers 3. ... Youll still need to determine the symptoms and how many users or portions of your wider network are affected. ... However, in this objective, network configuration settings on the remote station will be somewhat more important; bear in mind when which protocols are appropriate and the various authentication issues that can arise. ... 10, a firewall marks the difference between a public and private network. Realizing that your network is actually part of the larger Internet, anything behind the firewall (namely, your network) is a private network. Anything in front of it is a public network. Just as a structural firewall protects anything behind it from any fire that might start in front of it, a network firewall keeps intruders (hackers, clumsy surfers, corporate spies, etc) that might approach from in front of it from getting to the network behind it. A firewall is usually hardware, software, or a combination of the two that marks the boundary between your “private” network and the part of the Internet—which may even include part of your overall network—that remains “public.” How Intruders Get In • Logging on – Using stolen network login/password credentials. • Backdoors – A logically hidden access to a program, computer, or network, written directly into the code. ... For instance, a firewall will allow anyone with a correct login and password access to the network. ... A firewall can minimize those threats against which it is able to protect the network. ... The highest level of security would be to block everything, which obviously defeats the purpose of having a network, not to mention a firewall, in the first place. ... Setting up a DMZ (DeMilitarized Zone) A DMZ is is an area outside the firewall, in a portion of the network that remains in the public network. ... Most software-based firewalls will allow you to designate a directory on the gateway computer so that the network will know it’s the DMZ. ... The Methods Firewalls use one or more of these three methods to control traffic flowing in and out of the network: • Packet filtering – Packet headers are analyzed and compared against the set of filters you implemented when you configured the firewall. ... Note: the Proxy server also will examine requests for Internet access coming from an internal node and attempting to leave the network. ... A packet traveling from behind the firewall and trying to access the public network outside the firewall will be monitored for specific defining characteristics. ... • Improves network performance by functioning as a caching server. ... Types of Proxy Server: IP Proxy Hides IP addresses of all nodes on a network, sending instead its own IP address. This is better known as Network Address Translation (NAT). Web (HTTP) Proxy Handles Internet access requests on behalf of any node on the network. ... Many SMTP proxy servers have added network virus protection and will scan each e-mail for viruses. ... 10 Given a scenario, predict the impact of a particular security implementation on network functionality (e. ... ) Like adding screens to your homes windows can keep out more than flies, so also enhancing security on your network can keep out more than hackers. |
|||
To link to this page, copy the following code to your site:
Paper Information |
|||||
Title: network
|
|||||
Signup & Login |
|||||
If you don't currently have a login then Signup here |
|||||
| Pre-Written Papers | |||||
|
|||||
| Custom Papers | |||||
|
|||||
Copyright 2003-2008 doingmyhomework.com. All rights reserved.