System and method of accessing a document efficiently through multi-tier web caching

摘要

Upon receipt of a document request, a client assistant examines its cache for the document. If not successful, a server searches for the requested document in its cache. If the server copy is still not fresh or not found, the server seeks the document from its host. If the host cannot provide the copy, the server seeks it from a document repository. Certain documents are identified from the document repository as being fresh or stable. Information about each of these identified documents is transmitted to the server which inserts entries into an index if the index does not already contain an entry for the document. If and when this particular document is requested, the document will not be present in the server, however the server will contain an entry directing the server to obtain the document from the document repository rather than the document's web host.

主权项

1. A system for domain name server (DNS) caching comprising:
a memory, including a DNS cache configured to store DNS address records, wherein each DNS address record corresponds to a hostname; and one or more processing units, coupled to the DNS cache and configured to:
prioritize DNS address records in the DNS cache for self-refresh prior to expiration of the respective DNS address records, wherein the DNS address records in the DNS cache are prioritized for self-refresh in accordance with predefined criteria that include user visit frequency associated with IP addresses corresponding to the DNS address records in the DNS cache;in accordance with the prioritization of the DNS address records for self-refresh, initiate a DNS resolution request for a hostname of a respective DNS address record of the prioritized DNS address records; andupdate the respective DNS address record based upon a result of the DNS resolution request.