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Why can't I ping my test station? You can subscribe to this wiki article using an RSS feed reader.

11/17/2008 11:19 AM

Error: Test station at IP address <IP or FQDN> is not responding. Check the address and try again.

Symptoms

While attempting to ping a test station, I receive an error indicating that the test station is not responding.

Cause

  1. Wrong Test Station address
  2. Test Station communications are disallowed through a firewall or proxy
  3. Spartan Server DNS has cached an old address for this test station

Resolution

  1. Verify that the IP Address or Fully Qualified Domain Name (FQDN) used for this station is correct.  Once verified, execute ping operation again.  If problem persists, you may be experiencing difficulties communicating through a firewall or proxy (see Cause/Resolution #2).
  2. Spartan is unable to communicate to a test station located behind a firewall or proxy which disguises a test station address or blocks communications to port 3363 of the test station.
    • Verify that your firewall is configured to allow PING operations as well as TCP communications over port 3363 (NOTE: by default, these communications will be blocked by Windows Firewall.  See Windows Help for more information about allowing communications through Windows Firewall).
    • PLEASE NOTE: The current release of Spartan requires that test stations be recognizable by unique IP addresses within the intranet.  To communicate to a test station which is assigned a dynamic IP address (i.e. Rotating DHCP), use the station FQDN to resolve the address using DNS.
  3. Spartan Server has cached an old or invalid IP address for this test station.
    • The Spartan Server machine contains a local DNS lookup table cache which it uses to quickly identify devices on the network which it has spoken to recently.  The purpose behind this local cache is to avoid asking the local network for the same information repeatedly.

      By default, the default Time-To-Live (TTL) for each record in the cache is 1 day.  This means that each record will be recycled and re-acquired at least once every 24 hours.
    • If the local network is configured to assign a new DHCP lease to a workstation more than once every 24 hours, the local cache may inadvertantly store the machine's old IP address and become unable to communicate to the test station using its FQDN.
    • To aleviate this problem, the Windows system default TTL may be modified through the windows registry in Windows XP or Windows Server 2003.  The following DWORD registry key can be edited to limit the local cache TTL by a specified number of seconds (NOTE: if the key doesn't exist, it must be created and the system must be rebooted):

      HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNSCache\Parameters\MaxCacheTtl

    • The following registry key can be utilized to set the default TTL to zero, which effectively disables local caching on this machine.  If you are experiencing a caching problem, it is recommended that the TTL be disabled on your Spartan Server.

      DissableLocalCacheTTL.reg.unsafe

Summary


A Spartan Test Station must be visible to the Spartan Server through a unique IP address.  This address may be dynamically recognized using the Fully Qualified Domain Name (FQDN) of the test station.  If the DHCP lease on a test station is changed more frequently than the local DNS cache on the Spartan Server, the default Time-To-Live (TTL) for the Spartan Server machine must be modified to allow updated DHCP lease information to be acquired more frequently.

Keywords

ttl : time to live : fqdn : fully qualified domain name : ip address : ping : server : test station editor

 
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