4.0 Network Management

4.3 Given a scenario, use appropriate software tools to troubleshoot connectivity issues.

  • Protocol analyzer

  • Throughput testers

  • Connectivity software

  • Ping

    The PING utility tests connectivity between two hosts by sending an ICMP Echo Request to a destination host to verify IP connectivity. Ping can also be used to isolate network hardware problems and incompatible configurations by providing indicators of the general speed or reliability of network connections.

    Command options include:

    • -t : Pings the specified host until stopped
    • -a : Resolves addresses to hostnames
    • -n : Count Number of echo requests to send
    • -l : Adjusts the size of the ping packet
    • -w : Adjusts the time-out (in milliseconds)
    • hostname : Tests connectivity to a particular host

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  • Tracert/traceroute

    Traceroute is a utility program very similar to Ping, except that Tracert identifies the network path of test data sent to a remote computer, rather than the time it takes for each packet to return. It will list all the routers it passes through until it reaches its destination, or fails to and is discarded. In addition to this, it will tell you how long each 'hop' from router to router takes.

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  • Dig
    Dig (domain information groper) is a tool for interrogating DNS name servers. It performs DNS lookups and displays the answers that are returned from the name servers that were queried.

  • Ipconfig/ifconfig

    The IPConfig command line utility is used to display or set TCP/IP configuration settings of network interfaces including the IP address, subnet mask, default gateway, MAC address, and DNS names. It also helps with reconfiguration of your IP address through release and renew.

    To use Ipconfig in Windows 2000 or XP;

    • Begin with Start, and select Run. This opens the "Run Line" dialog frame. Type cmd on the line and press Enter to invoke the Command Prompt utility. At the command prompt, type ipconfig, and press Enter.

    In Windows 7;

    • Begin with Start, type cmd in the Search Bar and press Enter to invoke the Command Prompt utility. At the command prompt, type ipconfig, and press Enter.

    Optional switches for Ipconfig include:

    • /? Displays the Help menu for ipconfig.
    • /all Displays full configuration information.
    • /release Releases the IP address for the specified adapter.
    • /renew Renews the IP address for the specified adapter.

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  • Nslookup

    Nslookup.exe is a command-line administrative tool for testing and troubleshooting DNS servers. In its most basic usage, NSLookup returns the IP address with the matching host name.

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  • Arp

    Address Resolution Protocol (ARP) is a low-level network protocol used for the resolution of network layer IP addresses into corresponding link layer MAC (Media Access Control) addresses. ARP is the standard of identifying a host's hardware address when only its network IP address is known.

    ARP operates at Layer 2 of the OSI model allowing packets or frames on a local network to be delivered to physical (MAC) addresses, not IP addresses. When a machine attempts to communicate with another on the same local network, it will first check it's own ARP cache for the desired IP and MAC addresses. If it doesn't find the desired entry, it will broadcast an ICMP ping request for the IP address to every machine on the local network. If the intended target is online, a reply is returned with the proper IP address and physical address.

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  • Nbtstat

    Nbtstat (NetBios over TCP/IP) is designed to help troubleshoot NetBIOS name resolution problems. When a network is functioning normally, NetBIOS over TCP/IP resolves NetBIOS names to IP addresses.

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  • Netstat

    Netstat (Network Statistics) is a command-line tool that displays network connections (both incoming and outgoing), routing tables, and a number of network interface statistics. It is available on Unix, Unix-like, and Windows NT-based operating systems.

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  • Route
    Route displays and modifies the entries in the local IP routing table. Used without parameters, route displays help.