Why the inventory scan got succeed after vulscan.exe run.

Hi all.

Now we use the v8.7 SP2 Core server and support handreds of clients which are serveral versions.

Few years ago,We changed Core Server's IP address.(Same Name)

Now, I tried to test v8.6.1 client agent which was maden before changing Core Server's IP address.

After I installed it to the test machine,I could find the device name of that on the core server but I failed Inventory scan with GUI(it means that pointing the device -> right clicked -> Inventory scan).

the dialog said  "Lose connection" 

After that I run security scan from core server to the test device and then I retried to do inventory scan of it.

So the scanning  finished successfully.

I don't figure out Why the procedure was success after the vulscan.exe had been run on the client machine.

What I want to ask is the reason why the inventory scanning have gotten succeed after Inventory scan runs on the v8.6 agent.

Does any one have infomation about that ?

thanks.