I have access to a VPN network while I'm in my office. If I'm in the VPN I can access sites that my office network has blocked. Can the IT admins see that I'm going to those sites? And if so at what part of the network is it visible?
It really depends on what you really mean. Can they see what is in the packets? Probably not. Can they see that the traffic is encrypted and you are using a VPN? More than likely. Can they see your browser history? I would say it is safe to assume they would be able to. So in short, yes but not at the network level.
To my understanding:
- Some websites at Your company networks are blocked
- You access VPN which belongs to one of Your customers
If above is correct, Your company's IT staff might not see websites You visit. The "might" in previous sentence relates to how do You access this VPN. If the VPN is not fully tunneled (e.g. You can see hosts in customer's network, but You dont get their IP for accessing internet) then Your IT staff will see the traffic.
If the VPN connection is fully tunneled (You can see hosts + Your connection is fully routed through customer's network) then Your company's IT staff won't see anything as the connection is encrypted. But then, on the customer's network side, their IT staff might log Your connection as You use their network.
Moreover, customer's VPN server might log every request You do, every host You connect to etc.