# We've Re-Installed a Computer Will PerformanceGuard Recognize It?

> Whether PerformanceGuard still recognizes a computer after it has been re-installed.

Source: https://docs.capaone.com/performanceguard/troubleshooting/troubleshoot-server/we-ve-re-installed-a-computer-will-performanceguard-recognize-it/  
Product: PerformanceGuard — a separate CapaSystems product; do not apply this page to any other.

<font style="color: #404040;">We have re-installed a computer that has previously reported to PerformanceGuard. Will PerformanceGuard recognize the computer after we have re-installed it?</font>

<font style="color: #404040;">Yes, PerformanceGuard will recognize the computer based on the computer's MAC address, so unless you have also changed the computer's network adapter, you'll have continuous data about the computer in PerformanceGuard (that is from before as well as after you reinstalled the computer).</font>

<font style="color: #404040;">This of course also requires that you install the PerformanceGuard agent on the computer after you have re-installed the computer.</font>

<font style="color: #404040;">What if the computer runs in a virtual environment, for example if it is a Citrix server that runs on VMware[^®]? Such a server would very likely get a new MAC address if you re-install it.</font>

<font style="color: #404040;">It's correct that a server like that would get a different MAC address, so PerformanceGuard would not be able to recognize it based on the MAC address.</font>

<font style="color: #404040;">However, it's possible to change the way that PerformanceGuard recognizes such computers—technically called the agent lookup strategy—if you change a setting in the PerformanceGuard database so that PerformanceGuard will recognize computers by their computer names instead of their MAC addresses. Provided that the Citrix server in the example has kept its computer name, PerformanceGuard would then recognize it.</font>

:::caution
Note that the agent lookup strategy is a global setting, so if you change it, it will affect the way that PerformanceGuard recognizes all computers. We recommend that you contact your CapaSystems consultant if you want to change the agent lookup strategy.
:::