When the Master goes offline, the backup server will authenticate users and store entries in the log. When the Master comes back online, the databases reconcile with each other. The data stream between them is encrypted and the key changes every 10 minutes. Their packets are encrypted as well. It doesn't matter if you have users connecting from VPNs, dial-ups, Intranets or Extranets.
Most market leading products have a built in two-factor authentication compatibility.
Figure 2 Token-based security systems have been around for about 10 years. There are over 100 RSA Security partners who have built in agents to support SecurID two-factor authentication in their products. These entries are automatically generated and added to a log file for auditing purposes. Consideration should be taken with your Security Policy and should include procedures on how you to collect network logs. Network auditing is just as important.