Patent ID: 7552237

Claim:
A client computer system coupled via a network to a domain name server that changes order of a plurality of network addresses corresponding to a selected domain with each request to the domain name server for a network address corresponding to the selected domain, the client computer system comprising: (A) a resolver coupled to the domain name server, the resolver comprising: (A1) a cache containing a plurality of entries, at least one entry including a first list of network addresses corresponding to a selected domain that are retrieved from the domain name server; and (A2) a cache mechanism that changes order of network addresses in the first list of network addresses delivered from the cache according to at least one order change criterion when the at least one entry that includes the first list of network addresses satisfies a query, and that queries the domain name server if no entry in the cache satisfies the query, wherein the cache mechanism determines time to live for the first list of network addresses when the first list of network addresses is received from the domain name server, that determines whether the time to live is less than a specified minimum time to live, that sets the time to live to the specified minimum time to live if the time to live is less than the specified minimum time to live, and that writes the first list of network addresses and corresponding time to live to a cache entry; (B) at least one client application coupled to the resolver that queries the resolver to determine network addresses that corresponds to the selected domain.