Aging and scavenging of DNS resource records

• US 6,701,329 B1
• Filed: 09/14/2000
• Issued: 03/02/2004
• Est. Priority Date: 09/14/2000
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Schwartz, Eyal, Kwan, Stuart L. S., Gilroy, James M., Esibov, Levon A.
• Primary Examiner(s): Winder, Patrice
• Assistant Examiner(s): MASTRACCI, DARYL R
• Application Number:
  US09/661,480
• Time in Patent Office: 1,265 Days
• Field of Search: 707/200-206, 707/10, 709/203, 709/245, 709/223
• US Class Current: 1/1
• CPC Class Codes: H04L 61/4511 using domain name system [DNS]
• CPC Class Codes: H04L 61/4552 Lookup mechanisms between a plurality of directories; Synchronisation of directories, e.g. metadirectories
• CPC Class Codes: H04L 61/5076 Update or notification mechanisms, e.g. DynDNS
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users

Abstract

A method and system for aging and scavenging resource records in a DNS database is provided. DNS resource records that are stored in a DNS database are assigned the timestamps indicating the last time the records were updated. Clients (owners of the resource records) periodically refresh timestamps of the DNS resource records that they registered using standard dynamic DNS update protocol. The DNS server then periodically searches its database for the stale records and deletes them. DNS database zone parameters and DNS server parameters are configured to define when a timestamp for a resource record may be updated, when a resource record may be scavenged (deleted) and which server may perform scavenging of a zone. A non-refresh interval follows the timestamp, a refresh interval follows the non-refresh interval and a scavengable period follows the refresh interval. During the non-refresh interval, an authorized DNS server may neither refresh nor scavenge the associated resource record. During the refresh interval, an authorized DNS server may refresh, but not scavenge the associated resource record. During the scavengable period, the resource record may be scavenged, if the timestamp is not renewed in the meantime. The build up of stale resource records, or records that have outlived their utility, is thus prevented improving system performance and conserving system memory and resources.

Claims

1. A method for aging and scavenging domain name service (DNS) resource records in a DNS database, comprising:

configuring at least one DNS server and at least one zone in a DNS database with parameters for performing aging and scavenging according to predefined temporal intervals;

adding a timestamp to at least one resource record in said at least one configured zone when said at least one resource record is one of created, updated and refreshed;

determining the age of said at least one resource record;

determining in accordance with said determined age to which predefined temporal interval of a plurality of temporal intervals defined by said parameters said resource record belongs; and

scavenging said at least one resource record in said at least one zone with said at least one DNS server at a scavenging time determined by said parameters, if said at least one resource record'"'"'s age is such that the temporal interval to which said at least one resource record belongs is a temporal interval that permits scavenging as determined by said parameters.

2. A method according to claim 1, wherein said plurality of temporal intervals include a scavenging servers parameter that defines which servers may perform said scavenging.

3. A method according to claim 1, wherein said plurality of temporal intervals include a start scavenging parameter that defines a time delay before said scavenging so that all entities refreshing DNS records have a preset amount of time to refresh the records.

4. A method according to claim 1, wherein said plurality of temporal intervals include a non-refresh interval, immediately following said timestamp, during which an associated resource record may neither be refreshed nor scavenged.

5. A method according to claim 4, wherein said plurality of temporal intervals include a refresh interval, immediately following said non-refresh interval, during which an associated resource record may be refreshed, but not scavenged.

6. A method according to claim 1, wherein said plurality of temporal intervals include a scavenging interval, during which an associated resource record may be scavenged at a scavenging time defined by said parameters.

7. A method according to claim 6, wherein if a resource record associated with the scavenging interval is one of refreshed and updated, a new timestamp is applied to the resource record and aging of the resource record begins anew.

8. A method according to claim 6, wherein the scavenging interval for an associated resource record is ended upon one of refreshing, updating, and scavenging of said associated resource record.

9. A method according to claim 1, wherein at least one of said parameters defines how often said at least one DNS server may scavenge said at least one zone.

10. A method according to claim 4, wherein at least one of said parameters defines the length of said non-refresh interval.

11. A method according to claim 5, wherein at least one of said parameters defines the length of said refresh interval.

12. A method according to claim 6, wherein at least one of said parameters defines the starting time of the scavenging interval.

13. A method according to claim 1, wherein a request from a client computer may cause said DNS server to perform one of creating, updating and refreshing of a resource record in said at least one zone.

14. A method according to claim 1, wherein said parameters and plurality of temporal intervals are set to default values.

15. A computer-readable medium having computer-executable instructions for instructing a computer to perform the method recited in claim 1.

16. A plurality of data structures stored on computer-readable media associated with at least one zone of a DNS database and at least one DNS server in connection with which the method of claim 1 is performed, having parameters that define a non-refresh interval, a refresh interval and a scavenging period.

17. A modulated data signal for carrying information that encodes one of said plurality of data structures as recited in claim 16.

18. A computer system for performing aging and scavenging of domain name service (DNS) resource records, comprising:

at least one DNS server;

at least one zone of at least one DNS database;

a network connection to at least one client computer;

wherein at least one resource record in said at least one zone is given a timestamp when it is one of created, refreshed and updated, wherein parameters are configured for said at least one DNS server and said at least one zone that enable a determination of the age of at least one resource record in said at least one zone and a determination of to which of a plurality of time intervals said at least one resource record belongs, and wherein if said age is such that said at least one resource record belongs to a scavenging interval, said at least one resource record may be scavenged by said at least one DNS server at a scavenging time also defined by said parameters.

19. A computer system according to claim 18, wherein said plurality of time intervals include a scavenging servers parameter that defines which servers may perform said scavenging.

20. A computer system according to claim 18, wherein said plurality of time intervals include a start scavenging parameter that defines a time delay before said scavenging so that all entities refreshing DNS records have a preset amount of time to refresh the records.

21. A computer system according to claim 18, wherein said plurality of time intervals include a non-refresh interval, immediately following said timestamp, during which an associated resource record may neither be refreshed nor scavenged.

22. A computer system according to claim 21, wherein said plurality of time intervals include a refresh interval, immediately following said non-refresh interval, during which an associated resource record may be refreshed, but not scavenged.

23. A computer system according to claim 18, wherein if a resource record associated with the scavenging interval is refreshed or updated, a new timestamp is applied to the resource record and aging of the resource record begins anew.

24. A computer system according to claim 18, wherein the scavenging interval for an associated resource record is ended upon one of refreshing, updating, and scavenging of said associated resource record.

25. A computer system according to claim 18, wherein at least one of said parameters defines how often said at least one DNS server may scavenge said at least one zone.

26. A computer system according to claim 21, wherein at least one of said parameters defines the length of said non-refresh interval.

27. A computer system according to claim 22, wherein at least one of said parameters defines the length of said refresh interval.

28. A computer system according to claim 18, wherein at least one of said parameters defines the starting time of the scavenging interval.

29. A computer system according to claim 18, wherein a request from a client computer over said network connection causes said DNS server to perform one of creating, updating and refreshing of a resource record in said at least one zone.

30. A computer system according to claim 18, wherein said parameters and said plurality of time intervals include default values.

31. A method for determining whether to scavenge a resource record in a domain name service (DNS) database at a scavenging time, including:

retrieving the timestamp of the resource record in the DNS database;

adding a non-refresh interval to the timestamp to produce a first result;

adding a refresh interval to the first result to produce a second result; and

determining whether the current time is greater than the second result,

wherein if the current time is greater than the second result, the resource record is scavenged.

32. A method according to claim 31, further including:

determining whether the current time is greater than the first result but less than the second result,

wherein if the current time is greater than the first result but less than the second result, the resource record may be one of refreshed and updated, but not scavenged.

33. A method according to claim 31, further including:

determining whether the current time is greater than the timestamp but less than the first result,

wherein if the current time is greater than the timestamp but less than the first result, the resource record may be updated, but the resource record may not be scavenged and the resource record may not be refreshed.

34. A method according to claim 31, wherein the non-refresh interval and the refresh interval are assigned default values.