IP Address by fjzhangweiyun


             Karlie Meyer
              Kait Sharer
   Internet Protocol Address: exclusive number all information technology
    devices use which identifies and allows them the ability to communicate
    with each other on a computer network
   Dynamic IP Address
    ◦ Can change at any time
    ◦ Issued from a pool of IP addresses allocated by ISP or DCHP Server
    ◦ Computer automatically gets this number as it logs on to the network
   Static IP Address
    ◦ Fixed and never changes
    ◦ ISP provides a single static IP or a block of static IP’s
   IP version 4
    ◦ Currently used by most network devices
    ◦ Limited to 4,294,967,296 addresses
   IP version 6
    ◦ Estimated number of unique addresses =
    ◦ Can be written in the following formats:
         1080:0000:0000:0000:0000:0034:0000:417A
         1080:0:0:0:0:34:0:417A
         1080::34:0:417a
   Domain Name System (DNS): Allows the IP
    address to be translated to words
   Dynamic Host Configuration Protocol (DHCP):
    ◦ A computer networking protocol used by hosts to
      retrieve IP address assignments and other
      configuration information.
    ◦ Client-server architecture
    ◦ The client sends a broadcast request for
      configuration information. The DHCP server
      receives the request and responds with
      configuration information from its configuration
   Public IP address:
    ◦ Avoid online bans
    ◦ ISP may assign you an invalid address due to some
      technical glitch in their equipment
   Private IP address:
    ◦ Accidentally configured an invalid address
    ◦ Using a malfunctioning router that is providing bad
    ◦ Installing a new router and re-configuring your
      home network to use its default IP address range
   To change a static IP address, contact the ISP
    and work with their technical support to have
    them assign a new one
   To change a dynamic IP address:
    ◦ If your computer is directly connected to the
      Internet, you can attempt to release and renew the
      address using ipconfig or a similar utility
    ◦ Often, you will need to disconnect your modem
      from the Internet for a long period of time (many
      hours or a few days) before the ISP will assign a
      different dynamic IP address.
   Easier
   Static address: directly set a new IP address
    on the device
   Dynamic Address:
    ◦ release and renew the DHCP address on the client
    ◦ set up the router to use a different IP address range
    ◦ change one or more devices on the network from
      dynamic to static addressing
1.   Control Panel
2.   Network
3.   Find Network
     Connection to
     Internet (LAC)
4.   Right Click and
     select Properties
5.   Click Internet
     Protocol (TCP/IP)
     item in list
6. Click Properties
7. Click Use the
   following IP address:
   and enter the IP
   address, subnet
   mask, and default
   gateway information
8. Enter the same info
   for DNS servers
9. Click OK until done
   All information is
   provided by ISP
BUT if you are behind a router it gets more
 Static IP address should be assigned to the
• Configuring the router to to not get an IP address
  dynamically, but instead you'll enter the IP, gateway,
  subnet, and possibly DNS information by hand, using
  whatever approach your router uses for configuration.
• Port-forwarding
• Configure it to accept requests on
  certain "ports" and direct them to
  certain computers on your LAN.
   Bandwidth: the volume of information per
    unit of time that a transmission medium (like
    an Internet connection) can handle.
   Latency: refers to any of several kinds of
    delays typically incurred in processing of
    network data.
    ◦   Low latency network experiences small delay times
    ◦   High latency connection suffers from long delays
    ◦   Actual bandwidth is affected by high latencies.
    ◦   Excessive latency creates bottlenecks that prevent
        data from filling the network pipe, thus decreasing
        effective bandwidth
   A set of rules which is used by computers to
    communicate with each other across a
    network governing the syntax, semantics,
    and synchronization of communication.
   A protocol is a convention or standard that
    controls or enables the connection,
    communication, and data transfer between
    computing endpoints.
   Implemented by hardware, software, or a
    combination of the two.
   Set of communications protocols used for the
   Two-layer program
   Transmission Control Protocol (TCP):
    ◦ Higher layer
    ◦ Manages the assembling of a message or file into
      smaller packets that are transmitted over the Internet
    ◦ Messages are received by a TCP layer that reassembles
      the packets into the original message
   Internet Protocol (IP):
    ◦ Lower layer
    ◦ Handles the address part of each packet so that it gets
      to the right destination
   Program that allows applications on different
    computers to communicate within a local area
    network (LAN).
   Two communication modes:
    ◦ Session mode lets two computers establish a
      connection for a "conversation," allows larger
      messages to be handled, and provides error
      detection and recovery
    ◦ Datagram mode is "connectionless" messages must
      be smaller, and the application is responsible for
      error detection and recovery. Also supports the
      broadcast of a message to every computer on the
   Full-duplex data can be transmitted in both
    directions on a signal carrier at the same time
   Half-duplex data can be transmitted in both
    directions on a signal carrier, but not at the
    same time.
   Both imply a bidirectional line, or one that
    can move data in both directions
    Windows has two modes of operation – Workgroup and
   Workgroup:
    ◦ Peer-to-peer network, or each computer is sustainable on its own
    ◦ In order for a user to access resources on another workgroup
      computer, that exact user must be setup on the other computer
    ◦ Workgroups offer little security outside of basic access control.
    ◦ Workgroups are more than adequate for most small business and
      home use
   Domain:
    ◦ Trusted group of computers that share security, access control
      and have data passed down from a centralized domain controller
      server or servers
    ◦ Domain Controllers handle all aspects of granting users
      permission to login
    ◦ Use Active Directory which allows and even more centralized point
      for software distribution, user management and computer
    ◦ Most mid to large businesses will run in Domain mode
   HTTP (Hypertext Transfer Protocol):
    ◦ Set of rules for transferring files (text, graphic images, sound,
      video, and other multimedia files) on the World Wide Web.
    ◦ Application protocol that runs on top of the TCP/IP suite of
    ◦ Web browser is an HTTP client, sending requests to server
      machines. When the browser user enters file requests by either
      "opening" a Web file (typing in a URL) or clicking on a hypertext
      link, the browser builds an HTTP request and sends it to the IP
      address indicated by the URL. The HTTP daemon in the
      destination server machine receives the request and sends back
      the requested file or files associated with the request.
   FTP:
    ◦ simplest way to exchange files between computers on the Internet
    ◦ Used to transfer Web page files from their creator to the computer
      that acts as their server for everyone on the Internet
    ◦ Used to download programs and other files to your computer from
      other servers.
   POP3 (Post Office Protocol 3):
    ◦ Client/server protocol in which e-mail is received and held for you
      by your Internet server
    ◦ Built into most popular e-mail products, such as Eudora and
      Outlook Express. Also built into the Netscape and Microsoft
      Internet Explorer browsers
    ◦ “Store-and-forward” service
   IMAP (Internet Message Access Protocol):
    ◦ Provides the user more capabilities for retaining e-mail on the
      server and for organizing it in folders on the server
    ◦ POP and IMAP both deal with the receiving of e-mail
   SMTP (Simple Mail Transfer Protocol):
    ◦ Protocol for transferring e-mail across the Internet

   You send e-mail with SMTP and a mail handler receives it
    on your recipient's behalf. Then the mail is read using POP
    or IMAP.
    ◦ User command and an underlying TCP/IP protocol for
      accessing remote computers
    ◦ An administrator or another user can access someone else's
      computer remotely
    ◦ You log on as a regular user with whatever privileges you
      may have been granted to the specific application and data
      on that computer.
    ◦ Telnet is most likely to be used by program developers and
      anyone who has a need to use specific applications or data
      located at a particular host computer.
   HTTPS:
    ◦ Use of Secure Socket Layer (SSL) or Transport Layer Security
      (TLS) as a sublayer under regular HTTP application layering
    ◦ Encrypts and decrypts user page requests as well as the
      pages that are returned by the Web server
   LAN (Local Area Network):
    ◦ Group of computers and associated devices that share a
      common communications line or wireless link
    ◦ Connected devices share the resources of a single
      processor or server within a small geographic area
    ◦ Server has applications and data storage that are shared
      in common by multiple computer users. A local area
      network may serve as few as two or three users or as
      many as thousands of users
   WAN (Wide Area Network):
    ◦ Geographically dispersed telecommunications network
    ◦ May be privately owned or rented
    ◦ Inclusion of public (shared user) networks
   Hub:
    ◦ Place of convergence where data arrives from one or more directions and
      is forwarded out in one or more other directions
    ◦ Place where data comes together
   Switch:
    ◦ Device that channels incoming data from any of multiple input ports to the
      specific output port that will take the data toward its intended destination
    ◦ One or more switches are used to set up a dedicated though temporary
      connection or circuit for an exchange between two or more parties
    ◦ a switch determines from the physical device (MAC) address in each
      incoming message frame which output port to forward it to and out of
   Router:
    ◦ A device or, in some cases, software in a computer, that determines the
      next network point to which a packet should be forwarded toward its
    ◦ Connected to at least two networks and decides which way to send each
      information packet based on its current understanding of the state of the
      networks it is connected to
    ◦ Often included as part of a network switch
   A virtual private network (VPN) is a network that
    uses a public telecommunication infrastructure,
    to provide remote offices or individual users with
    secure access to their organization's network
   The goal of a VPN is to provide the organization
    with the same capabilities, but at a much lower
   The protocols, by encrypting data at the sending
    end and decrypting it at the receiving end, send
    the data through a "tunnel" that cannot be
    "entered" by data that is not properly encrypted
   Plenum
    ◦ In buildings with computer installations, the plenum space is
      often used to house connecting communication cables
    ◦ Often made of Teflon and is more expensive than ordinary cabling
    ◦ In the event of fire, its outer material is more resistant to flames
      and, when burning, produces less smoke than ordinary cabling
    ◦ Both twisted pair and coaxial cable are made in plenum cable
   PVC
    ◦ Software-defined logical connection in a network such as a frame
      relay network
    ◦ Feature of frame relay that makes it a highly flexible network
      technology is that users can define logical connections and
      required bandwidth between end points and let the frame relay
      network technology worry about how the physical network is used
      to achieve the defined connections and manage the traffic
    ◦ The end points and a stated bandwidth called a Committed
      Information Rate (CIR) constitute a PVC
    ◦ Multiple PVCs share the same physical paths at the same time
   UTP (Unshielded Twisted Pair):
    ◦ Most common kind of copper telephone wiring
    ◦ Ordinary copper wire that connects home and many
      business computers to the telephone company
    ◦ Each signal on twisted pair requires both wires
    ◦ Twisted pair is sometimes installed in two or more pairs,
      all within a single cable.
    ◦ Although twisted pair is often associated with home use,
      a higher grade of twisted pair is often used for
      horizontal wiring in LAN installations because it is less
      expensive than coaxial cable
   STP (Shielded Twisted Pair):
    ◦ Special kind of copper telephone wiring used in some
      business installations
    ◦ Twisted pair is enclosed in a shield that functions as a
   Fiber to the home (FTTH):
    ◦ Installation and use of optical fiber from a central point directly to
      individual buildings such as residences, apartment buildings and
      businesses to provide unprecedented high-speed Internet access.
      FTTH dramatically increases the connection speeds available to
      computer users
    ◦ Implementing FTTH on a large scale will be costly because it will
      require installation of new cable sets over the "last links" from
      existing optical fiber cables to individual users
   Coaxial Cable:
    ◦ Copper cable widely installed for use in business and corporation
      Ethernet and other types of local area network
    ◦ “Coaxial" because it includes one physical channel that carries the
      signal surrounded (after a layer of insulation) by another
      concentric physical channel, both running along the same axis
    ◦ Outer channel serves as a ground
    ◦ Can be placed in a single outer sheathing and, with repeaters, can
      carry information for a great distance
   RJ45:
    ◦ Single-line jack for digital transmission over ordinary phone wire, either
      untwisted or twisted
    ◦ Eight pins or positions
    ◦ Two varieties of RJ-45: keyed and unkeyed
       Keyed has a small bump on its end
       Both jack and plug must match
   RJ11:
    ◦ Most common telephone jack
    ◦ Can have six conductors but usually is implemented with four
    ◦ Likely to be the jack that your household or office phones are plugged into
      from the ordinary "untwisted" wire people are most familiar with
    ◦ Four wires are usually characterized as a red and green pair and a black
      and white pair
       Red and green pair typically carry voice or data
       Black and white pair may be used for low-voltage signals such as phone
    ◦ A computer that uses a dial-up modem to connect to a network is usually
      plugged into an RJ-11 jack
   Server:
      Web, ftp, email, application server
    ◦ Provides service to client(s)
      email exchange
      web / database access
   Client:
      browser, email, online chat
    ◦ Initiates request for some service
   All communication through server
   Clients do not communicate directly
+   Maintenance
+   Security
+   Centralized server / data

–   Overload
–   Centralized server
   No dedicated server
   End systems directly communicate
    ◦ Switch roles of client & server
   More peers = better performance

+   Shared resources
+   No Single point of failure
–   High Bandwidth usage
–   Security
P2P   Client / Server
   Centralized server
    ◦ Find IP address of remote party / peer
    ◦ “controls” communication
   Direct client – client connection
    ◦ not through server

   Skype
   Instant messaging
   High-speed Internet         Access limited to
    access                       phone line bandwidth
    ◦ exceeding 200 Kbps         ◦ 56 Kbps max
   “Always On”                 Initiate connection
   More reliable               Dynamic IP address
   Wider range of              Less vulnerable to
    frequencies                  attacks
   Simultaneous access to      Difficult to download
    voice & data                 multimedia files
    communication               Less cost
    ◦ splitter
   DSL (Digital Subscriber Line)
    ◦ existing copper telephone lines
    ◦ Kbps – Mbps
   Cable
    ◦ Coaxial cables
    ◦ 1.5 Mbps +
   Fiber to the Home (FTTH)
    ◦ Converts data signals to light & sends them through glass
    ◦ Speeds exceed DSL / Cable by hundreds of Mbps
   Satellite
    ◦ Provides wireless broadband to remote areas
    ◦ 500 Kbps (download) & 80 Kbps (upload)
    ◦ Extreme weather can disrupt service
   High-speed Internet service via wireless
    ◦ Radio waves / signals
   Speeds roughly equivalent to wired
    broadband access
    ◦ 1.5 Mbps data rate
Standard          802.11a     802.11b        802.11g               802.11n

Speed             54Mbps      11Mbps      54Mbps (108)         100Mbps (600Mbps)
Range              150ft       300ft           300ft                 300ft

Frequency          5GHz       2.4GHz         2.4GHz                2.4-5GHz

Security               SSID, MAC Filtering, WEP, WPA (TKIP), WPA2 (AES)

Compatibility     802.11a     802.11b       802.11g/b             802.11n/g/b
Spread Spectrum
   method          DSSS        DSSS           OFDM                  OFDM
Mode                                Ad Hoc or Infrastructure
   WEP (Wired Equivalent Privacy)
    ◦ Algorithm used to secure wireless networks
      Authentication
      Data encryption
   WPA (WiFi Protected Access)
    ◦ Encrypts wireless traffic
      Protects against eavesdropping
    ◦ More secure than WEP
   Dynamic Host Configuration Protocol
    ◦ Retrieve IP address assignments
    ◦ Configuration information
    ◦ Client / server architecture
      Client broadcast request for configuration info
      Server responds from configuration database
      Configure DHCP
    ◦ Add new machines to network
      Given unique IP Address
   Wireless technology
   Exchanges data over short distances
   PANs
   Uses frequency-hopping spread spectrum
    ◦ Transmits data into chunks
    ◦ 2402-2480 MHz range
   Communicate with up to 7 devices
    ◦ Mobile phones, laptops, GPA, digital cameras,
      printers, PCs, video game consoles
   Network type
    ◦ DSL, cable, Fiber, etc
    ◦ Desired speed
   Hardware requirements
    ◦ Network adapters
       Connect computers to network to communicate
    ◦ Hubs & switches
       Ethernet
    ◦ Routers & Access Points
       Share single connection between multiple computers
    ◦ Modems
       Send / receive information over telephone & cable
    ◦ Network Cables
       Connect computers & hardware
   provides networked computers with the
    ability to share a single connection to the
   If you have multiple computers, you can use
    ICS to allow you and others on your local area
    network (LAN) to perform different tasks
   For example, one person can send and
    receive e-mail messages, while another
    person downloads a file, and another person
    browses the Internet
   Multiple users can gain access to the Internet through a single
    connection by using Dial-Up Networking and local networking.
   Connected devices receive transparent network configuration
    by using Domain Name System (DNS) and Dynamic Host
    Configuration Protocol (DHCP) to resolve Internet names
   Any IP-attached device can connect, including older Windows-
    based clients, non-Windows-based clients, Microsoft Windows
    98-based clients, and Microsoft Windows 2000-based clients,
    with no additional client software required.
   Connected devices and software have comprehensive protocol
    support. For example, you can play Internet games without
    additional configuration, or you can use Point-to-Point
    Tunneling Protocol (PPTP) and Virtual Private Networking (VPN)
    to gain access to your corporate network.
   DHCP Allocator - A simplified DHCP service that assigns
    the IP address, gateway, and name server on the local
   DNS Proxy - Resolves names on behalf of local network
    clients and forwards queries.
   Network Address Translation (NAT) - Maps a set of
    private addresses to a set of public addresses. NAT
    tracks private-source IP addresses and public-
    destination IP addresses for outbound flows. It changes
    the IP address information and edits the required IP
    header information dynamically.
   Auto-dial - Automatically dials connections.
   Application programming interfaces (APIs) - For
    configuration, status, and dial control for programs.
   Your ICS network is a type of local area
    network that relies on a single computer
    called a gateway, through which all other
    computers and TCP/IP-capable devices
    connect to the Internet.
   The hardware and software needed to set up a home
    network includes:
    ◦ A primary computer, called a gateway, that provides
      network connectivity to the Internet. This computer must
      be running Windows 98 Second Edition, Windows 2000, or
      Windows Me with Internet Connection Sharing enabled.
    ◦ One or more computers running Windows 95, Windows 98,
      Microsoft Windows NT 4.0, Windows 2000, or other TCP-IP
      enabled client software.
    ◦ Devices that are capable of connecting to the Internet.
    ◦ A network connection device for each computer
    ◦ .Cabling and hubs, depending on the type of connection
      devices you use.
    ◦ A single modem (or an ISDN or ADSL line) for the entire
    ◦ Internet browser software and TCP/IP drivers installed on
      each device that shares the connection.
   You can enable Internet Connection Sharing
    by using the Add/Remove Programs tool in
    Windows 98 Second Edition or Windows Me:
    ◦ Click Start, point to Settings, click Control Panel,
      and then double-click Add/Remove Programs.
    ◦ On the Windows Setup tab, double-click Internet
    ◦ Click to select the Internet Connection Sharing
      check box, and then click OK.
    ◦ Click OK, and then follow the instructions on the
      screen to run the Internet Connection Sharing
Basic tools:
 Network Diagnostics in Help and Support

  ◦ Contains detailed information about the network configuration and
     the results of automated tests.
 Network Connections folder

  ◦ Contains information and configuration for all network connections on
     the computer. To locate the Network Connections folder, click Start,
     click Control Panel, and then click Network and Internet Connections.
 IPConfig command

  ◦ Displays current TCP/IP network configuration values, updates, or
     releases, Dynamic Host Configuration Protocol (DHCP) allocated
     leases, and display, register, or flush Domain Name System (DNS)
 Ping command

  ◦ Sends ICMP Echo Request messages to verify that TCP/IP is configured
     correctly and that a TCP/IP host is available.
   Make Sure You Have Correct IP Information:
    ◦ Make sure you have the correct IP scheme for your
      network. This would include the:
        IP Address
        Subnet Mask
        Default Gateway
        DNS Servers
    ◦ IP Config Command
      Displays current TCP/IP network configuration values,
       updates, or releases, Dynamic Host Configuration Protocol
       (DHCP) allocated leases, and display, register, or flush
       Domain Name System (DNS) names.
      FOR: Win9x - Start / Run / command;
       Windows2000/XP/Vista - Start / Run / cmd
    ◦ Then run IPCONFIG /ALL.
   IP Config Command
   Possible causes for not getting an IP address
    assigned are:
    ◦ Defective cable, network card or port on the router.
      Make sure you are using all known working
    ◦ Your router is not configured for DHCP (which
      would automatically be assigning IP addresses).
Basic ping tests:
 Using the command prompt
 ◦ Try pinging the router's IP address
   e.g. ping
 ◦ If you get a reply, then your connection to the
   router is working.
 ◦ If you don't get a reply, then you need to double
   check your network card, cable, port on the router.
   You might also see if any other computers on the
   network can do the same.
Basic ping tests:
 Try pinging an external site by IP address
    ◦ e.g. ping
   If you get a reply, then you have a connection to
    the Internet.
   If you don't get a reply, there are several things
    you can try:
    ◦ Double check that the router is connecting to the Internet.
      Typically you can access the router through your web
      browser and check it's status.
    ◦ Take the power off your DSL/Cable modem and Router.
      Plug the modem back in a wait a minute or so. Plug the
      router back in and wait a minute or so. Then restart your
Basic ping tests:
 Try pinging an external site by Name
    ◦ e.g. ping www.yahoo.com
   If you get a reply, then you have a connection to
    the Internet and DNS is working
   If you don't get a reply, there are several things
    you can try:
    ◦ Double check your DNS entries
    ◦ You many need to use the same DNS IP address that
      your ISP or Router is using.
    ◦ On rare occasions your ISP has problems with their DNS
      servers. But that is rare in comparison to misconfigured
Advanced tools:
 Hostname command
    ◦ Displays the name of the host computer.
   Nbtstat command
    ◦ Displays the status of current NetBIOS over TCP/IP connections,
      updates the NetBIOS name cache, and displays the registered
      names and scope ID.
   PathPing command
    ◦ Displays a path of a TCP/IP host and packet losses at each router
      along the way.
   Route command
    ◦ Displays the IP routing table and adds or deletes IP routes.
   Tracert command
    ◦ Displays the path of a TCP/IP host.
   To view the correct command syntax to use with each of
    these tools, type -? at a command prompt after the name
    of the tool.
Automated troubleshooting
 For most issues that involve Internet connectivity,
  start by using the Network Diagnostics tool to
  identify the source of the issue. To use Network
  Diagnostics, follow these steps:
 ◦ Click Start, and then click Help and Support.
 ◦ Click the link to Use Tools to view your computer
   information and diagnose problems, and then click
   Network Diagnostics in the list on the left.
 ◦ When you click Scan your system, Network Diagnostics
   gathers configuration information and performs
   automated troubleshooting of the network connection.
 ◦ When the process is completed, look for any items that
   are marked "FAILED" in red, expand those categories,
   and then view the additional details about what the
   testing showed.
   Start by rechecking your physical connections
   verify that your client's wireless adapter is installed and working
   verify that your wireless router's LAN settings are correct
   verify your client's TCP/IP settings
   Once your client has a valid IP address, use "ping" to verify network
   If your wireless client still cannot connect, get a valid IP address, or ping
    your router, it's time to consider wireless-specific problems
   If a matched wireless client and router can "hear" each other but still
    cannot connect or exchange traffic, look for a security mismatch
   Ensure RADIUS is working
   If RADIUS is working but the client's access requests are rejected, look
    for an 802.1X Extensible Authentication Protocol (EAP) or user login
   If your wireless client connects and pings successfully, but encounters
    intermittent network connectivity problems (e.g., some pings work,
    some fail), you may be experiencing poor signal strength, RF
    interference, or disconnection caused by AP roaming.
   Microsoft Support
    ◦ http://support.microsoft.com/kb/314067
    ◦ http://support.microsoft.com/kb/306126
    ◦ http://support.microsoft.com/kb/234815
   Bob Cerelli’s Windows Page
    ◦ http://www.onecomputerguy.com/networking/troubleshoo
   Wireless network troubleshooting: Connectivity By
    Lisa Phifer
    ◦ http://searchnetworking.techtarget.com/news/article/0,28
   Wikipedia
    ◦ http://www.wikipedia.org
   Search Networking.net
    ◦ http://searchnetworking.techtarget.com/
   What it is.com
    ◦ http://whatis.techtarget.com/

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