parallel to a network 420 such as the internet redundancy is provided by conventional dns procedures that is in dns redundant name servers are required by the dns specification if a query addressed to one of the redundant name servers does not receive a response the same query may then be addressed to another name server the same result holds true in fig4 if one of the physical firewall machines 407 or 408 is down the other machine enables normal operation to continue the configuration of fig4 however further allows the physical firewall machines 407 and 408 to share the aggregate processing load of current connections load sharing may be achieved in the following manner each of the dns modules of all of the machines receive all dns queries because the machines are connected in parallel presumably the dns module of the machine that is least busy will be the first to respond to a query an ensuing connection request is then mapped to a virtual host on the responding least busy machine as the popularity and use of the internet continues to grow there is a concern that all available addresses will be used thereby limiting further expansion an important result of ddns is that network addresses may be reused on network segments between which at least one firewall intervenes more particularly the addresses which are employed on opposite sides of a firewall are mutually exclusive of one another to avoid routing errors referring again to the example of fig1 users of the.