As a network architect, you have been asked to design a network infrastructure for a financial services provider that requires extremely high levels of security due to the sensitive nature of the data being processed. The client also demands that certain systems must remain operational and isolated even in the event of a catastrophic network failure. Which of the following solutions would BEST meet these requirements?
Implementing a Virtual Private Network (VPN) for all internal communications
Deploying an Intrusion Prevention System (IPS) throughout the network
Creating logical segmentation of the network using VLANs
Implementing an air-gapped network for those critical systems