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There is a symptom where Guru slows down when the network's DNS server does not respond to reverse DNS requests (host <IP> command). This symptom could appear running a Tester (EPC) or from a Virtual Workstation and applies to all OS/2, eComStation and ArcaOS generations of the OS.



Symptom
Guru performs slowly. All activities from launching a Short Cut to opening a test plan can be slowed while Guru waits for reverse DNS queries to resolve.

Root Cause
When any network connection is made, OS/2 performs a low level reverse DNS query to validate the hostname matches the IP address. The query has a time-out that when the DNS server responds slowly or does not respond at all will impact the normal ability for Guru to retrieve updates from the Guru server. This happens even if an IP address is used to make the connection.

To Confirm Issue:
1. Open a Command Window
2. Enter "host <Guru IP Address>". (replace <IP> with the IP address, like 10.22.33.44).
3. Interpret Results. A functional DNS server should respond quickly with a hostname and IP address (Figure 1, top), otherwise it will respond with "Can not resolve <IP> to a name", indicating the solution or work-around should be implemented (Figure 1, bottom) to avoid symptoms.

Figure 1: Host command output (top = good, bottom = bad)
Figure 1

Solution 1 DNS:
Implement a DNS server on the network that correctly responds to reverse DNS queries. This may be impossible to implement if the network architecture can not support it.

Solution 2 Local Hosts:
Updating the local hosts will quickly resolve the reverse DNS query locally, improving network performance of Guru. Follow the Update Local Hosts for all hostnames/IP address connections used by Guru. RI recommends using an alias with "-local" added to the end of the actual Hostname to remind users that this setting is being used, i.e. "guruServer01" has an alias of "guruServer01-local" and then the hostname with the "-local" part (i.e. "guruServer01-local") is used in the Address field when editing connections with Guru Address Book Admin. This solution may be temporary and have to be done any time the Guru Server's IP address changes.

It is important to note that the reverse DNS lookup has to succeed for any IP address used, even if the IP address is used in by the Guru connection.

To Update Local Hosts
1. From the OS task bar, navigate to System Settings > Network > TCP/IP > TCP/IP Configuration .  
2. Select the Host Names tab at the top then Hosts tab on the bottom.
3. Add a new entry or select an existing one and choose Edit. Set the correct IP address (i.e. 10.22.33.44) in the IP Address field, enter "guru" for the name and "guru-local" as the aliases and press OK.
4. Confirm this is working by opening a command window and typing "

To Update Guru Connections
1. Log in to Guru and choose Apps > Guru Address Book Admin.
2. If there are no entries, choose New Remote Address and enter "Guru" as Name, "guru-local" in Address and change Address Type to "backup".
3. Repeat step 2, but change address Type to "update".
4. Now choose System > Shutdown from Guru to have it close and restart automatically. The Logon/System button should now be green, indicating it is connected to the update Guru.
Note: If this Guru ID was ever used with this Guru Server before, there is a strong chance that old guru connections still exist and are now copied to the local guru. Remove the duplicate entries with the Delete Selected button in Guru Address Book Admin. You may have to select the entry and press Delete and wait for it to be removed. Because the query also displays objects on the server, the display may need to be refreshed after the obsoleted object is backed up to the server. To confirm the entry has been backed up to the server, check and uncheck "Show Local Addresses" to refresh the list until the deleted entry is removed.

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