All zones settings

When the Zones node is highlighted in the Load Generators group box, the Zones Settings dialog is displayed with:

• a click on the wrench-like advanced Settings button, or
• the Settings context command

  

DNS

Overriding DNS is useful if you need to run tests on a pre-production environment or on a specific cluster node of a production environment.

It is possible to configure IP addresses to override DNS resolution and distribute them to all Load Generators of all zones. Therefore, no DNS resolution will be performed for these host names.

IP addresses v4 and v6 are handled.

• To override DNS for all zones

1. Check the option Enable DNS overriding.
2. In the Hostname field, enter or select a hostname among all the servers defined in the project.
3. In IP Addresses, enter IP addresses directly in the field or click the pencil icon to open a text area dialog.

   Accepted separators are: comma, semi-colon, space, carriage return.

• Information: If you configure several IP addresses, a random IP from the list will be used.

  

Time to live of DNS cache

The Time to live (TTL) of DNS cache for Load Generators is set by default to 30 seconds. You can choose to set a different value.

Notes

• If the value is set at 0, there will be no cache: DNS resolution will be performed every time.
• If the value is set at -1, the IP addresses will never expire.
• If the value of the DNS cache TTL set for Load Generators is inferior to the value of the DNS cache TTL of the operating system running on the machine, the value configured will not be taken into account. To take it into account, you need to update the DNS cache TTL of the OS.

To update the DNS cache TTL of your machine OS, refer to the specific documentation of the operating system.

• Example: To set the DNS cache TTL on Windows 7 OS

1. Start Registry Editor (Regedit.exe).
2. Locate and then click the following key in the registry:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dnscache\Parameters

3. On the Edit menu, point to New, click DWORD Value, and then add the following registry values:

   Value name: MaxCacheTtl

   Data type: REG_DWORD

   Value data: If you lower the Maximum TTL value in the client's DNS cache to 1 second, this gives the appearance that the client-side DNS cache has been disabled.

• To set the TTL of DNS cache for Load Generators

• Enter a value in seconds in the Load Generator DNS cache TTL field.