It is possible for a IP network to configure two DHCP servers, one as main (primary) server and the other as secondary. During the normal working only the primary server answers the requests, while the secondary one synchronizes its BD with the primary, if the primary fails the secondary shall assume its service. Communication between the servers is made from the network ports which may be customized. One of the ports shall be attending the connections from the secondary server and the other one shall be attending the connections from the main server. (Figure 7.33)
iPortalMais
