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Troubleshooting Networks (Network Issues (Incorrect IP Configuration/Gatew…

- - - - Duplicate Problem
        Log into users comp
        Log in under different user
      - On site
        Identify Symptoms first hand
      - Remote
        Question Users
        Close-ended ?s for experienced users
        Open-ended ?s for novice users
  - - - Top-to-bottom OSI Model Approach
      - Bottom-to-top OSI Model Approach
      - Divide and Conquer
        
        As you gather information for troubleshooting, a general sense of where the problem lies should manifest. Place this likely cause at the appropriate layer of the OSI model and begin to test the theory and related theories at that layer.
  - - - Escalate the Problem
        
        Inform other parties for guidance
        
        Pass job off to another authority who has control over device/issue
      - Establish New Theory
        Return to step 2
- - - - ipconfig and ifconfig
        
        ipconfig The ipconfig command is used i*n Windows to display the IP address information of the system.
        • ipconfig /all Displays all TCP/IP settings and the MAC address
        • ipconfig /displaydns Displays the DNS resolver cache
        • ipconfig /flushdns Clears out the DNS resolver cache
        
        ifconfig The ifconfig command displays or sets settings on a network card on a UNIX/Linux/OS X system.
        • ifconfig Displays the network card and IP settings
        • ifconfig eth0 up Enables the first Ethernet card
        • ifconfig eth0 down Disables the Ethernet card
      - ping
        test the connection between two nodes
        Uses ICMP
        
        Can test availability of Sites using FQDNs(Google.com)
        Use to test DNS
        
        Unknown host
        This message means, “I don’t know the IP address!” You probably specified an invalid/unused DNS name.
        
        Destination host unreachable
        This message means, “I can’t get to that IP address.” In this case, you should check for possible routing problems—for example, have you specified a default gateway?
        
        ping –t
        tells ping to run indefinately
        
        ping -6
        use IPv6
      - tracert
        traces the route between two hosts
      - pathping
        ombines the functions of ping and tracert and adds some additional functions.
      - netstat
        enables a network tech to examine network statistics about a system
        Listening ports or established connections
        
        -a
        ALL connections and listening ports
        
        -b
        exe involved in creating each connection of listening port
        
        -e
        ETHERNET Stats
        
        -f
        Fully Qualified Domain Names (FQDN) for foreign addresses
        
        -n
        Addresses and ports in NUMERICAL form
        
        -p protocol
        Shows connections for protocol specified
        
        -o
        OWNING process ID associated with each connection
        
        -r/route print
        ROUTING table
        
        -s
        Per-protocol Stats
        
        -t
        Current Connection offload State
        
        -interval
        Redisplays selected stats, pausing interval seconds between each display
      - nbtstat
        enables a network tech to check information about the NetBIOS name
        
        -a
        lists remote machine's name table given it's name
        
        -A
        lists temote machine's name table given its IP address
        
        -c
        lists NBT's cache of remote machine names and their IP addreses
        
        -n
        lists local NetBIOS names
        
        -R
        Purges and reloads the remote cache name table
      - nslookup
        provides a command-line utility for diagnosing DNS problems
      - arp
        helps diagnose problems associated with the Address Resolution Protocol (ARP). CompTIA refers to the output of the arp command as the MAC address lookup table, while most folks would just call it the arp cache or arp table.
    - - Protocol Analyzer
        Lets you look at protocols running at different levels of network
        helps you determine slowdowns on a network by giving you an idea of excess or unexpected traffic
      - Wifi Analyzer
        documents all existing wireless networks in the area
        Handheld tool or software on laptop
      - Speed Test Sites
      - Looking Glass Sites
        Runs diag from outside of the network
        ping, traceroute, etc
  - - - Certifiers
        will report speed and duplex settings
- - - - Omnidirectional
        Radiates outward in all directions from WAP
      - Unidirectional
        Directs signal in specific direction
      - Patch
        Flat plate shaped antennas
        Generates half sphere beam
        Always on walls