4.2 Given a scenario, analyze and interpret the output of troubleshooting tools - Paiet/Tech-Journal-for-Everything GitHub Wiki

4.2 Given a scenario, analyze and interpret the output of troubleshooting tools

Command line tools 1
- ipconfig
  - Most common troulbeshooting options:
    - ipconfig /release
    - ipconfig /renew
    - ipconfig /all
  - IP Configuration utility developed by Microsoft Available on all versions of MS operating systems
  - Displays current TCP/IP information such as...
    - Host IP address
    - DHCP
    - Static
    - Subnet mask
    - Default Gateway
    - DNS settings
      - Allows you to work with the local DNS client
        resolver cache which is a local repository
        of recently looked up DNS records for quick access
      - ipconfig /displaydns :Displays the contents of the resolver cache
      - ipconfig /flushdns :Removes all entries in the resolver cache
      - ipconfig /registerdns :Manually kick off an update of the host's IP address/hostname with its DNS server
    - Requires that the DNS server supports dynamic record updates
- ifconfig
  - Much of the same information as ipconfig
    - Static/dynamic TCP/IP information
      - IP addresses
      - Subnet mask
      - Default Gateway
  - More capabilities
    - Doesn't just display IP info, but can set ip info
      - ifconfig eth0 192.168.0.2
      - ifconfig eth0 netmask 255.255.255.0
        
        Combine commands...
        
        ifconfig eth0 192.168.0.2 netmask 255.255.255.0
    - Able to enable/disable network interface adapter
    - Can disable ARP caching
    - Can put interface into PROMISCUOUS mode
  - Both ipconfig and ifconfig help you to track down networking issues
    - This is done by looking at the output of the respective command
      - Is there an IP address assigned?
      - Is the IP address correct for the IP scheme?
        
        APIPA? (169.254.x.x)
      - Is the subnet mask correct?
      - Is the default gateway set correctly?
      - Is the DNS info set correctly?
- netstat
  - Network tool that displays the status of network connections (NETwork STATistics)
    - TCP/UDP connections (incoming and outgoing)
    - Routing table info
    - Protocols
    - Local and remote addresses
  - This is helpful when troubleshooting
    - Network protocol ports
      - Is the correct port being used
    - Connection integrity
      - Is there a problem with the connection?
      - What are the TX/RX numbers?
        
        0 bytes sent/received would be a problem netstat -e -t 5
    - Look for problems with the NIC or network
      - High error count = NIC issue or high bandwidth utilization
    - Check for routing issues netstat -r
    - Also great for discovering rogue programs that are creating secret network connections netstat -o along with task manager details tab. or netstat -b (from administrative cmd)
  - ping/ping6/ping -6
    - ping6 (mac), ping -6 (forces IPv6), ping (IPv4)
    - Checks the connectivity through the network path of one host to another
    - ICMP ECHO/REPLY
    - ping itpro.tv
    - ping -6 2001:0:9d38:90d0:30d0:1f5e:f5ff:fdf0
- tracert/tracert -6/traceroute6/traceroute -6
  - Displays the path or route that is taken from one host to another
    - Helps troubleshoot connection issues
  - Each router hop that is taken by the packet will be displayed to the screen
  - Seeing where the packets stop can help you discern where the problem device may be
  - tracert itpro.tv (Windows)
  - traceroute itpro.tv (Linux)
- nbtstat - NetBIOS utility - not routable - options are case sensitive - Flat name resolution - superseded by DNS - must still pay attention due to options
  - nslookup
    - Name Server Lookup tool
    - Will lookup and return the different types of DNS records which match hostnames to IP addresses
      - A records
      - MX records
        
        Helps determine whether or not DNS is working properly
    - Has 2 modes of operation
      - Interactive
      - Non-interactive
      - Server *server address*
        
        Changes the default lookup server used
        
        Allows you to test the alternate server
        
        set debug
        
        Returns more info about the lookup
        
        set d2
        
        Returns even more info about the lookup

nslookup www.itpro.tv (query A and PTR records)
nslookup www.itpro.tv 8.8.4.4 (query A and PTR from another dns server)
nslookup
set type=mx
itpro.tv

arp arp -a - Address Resolution Protocol - Maps Layer 3 IP addresses to Layer 2 MAC addresses - Allows PC to use Layer 3 over a Layer 2 network - Both static and dynamic entries - Trouble with dynamic entries + ARP cache may have multiple entries for the same host causing conflicts + Incorrect entries
MAC address lookup table - show mac-address table - Makes sure that the switch is actually seeing a host as connected to a port + Also good at checking for bad switch ports - Verifies that the host/port correlation is correct
pathping: helps to find connection uses that may not show up using other latency tests.
- pathping itpro.tv (This may take some time to run, may need to do before episode begins.)
Line testers
Certifiers
Multimeter
- Voltage (DC or AC)
- Resistance (OHMs)
- Current (Amps)
Cable tester
Light meter
- Used for testing different wavelengths over fiber optic cable
Toner probe
Speed test sites
- [Speedtest.net][1]
- [Bandwidth Place.com][2]
Looking glass sites
- [cogentco.com][3]
- Test: BGP, US-Washington,DC, www.itpro.tv
WiFi analyzer
- identify APs
- display coverage
- SSID
- 802 spec
Protocol analyzer
- Wireshark [1]:http://www.speedtest.net/ [2]:http://www.bandwidthplace.com/