Method and apparatus for domain name service request resolution

• US 6,526,450 B1
• Filed: 04/17/2001
• Issued: 02/25/2003
• Est. Priority Date: 11/19/1998
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Sitaraman, Aravind, Lou, Shuxian, Zhang, Shujin
• Primary Examiner(s): Coulter, Kenneth R.
• Application Number:
  US09/837,786
• Time in Patent Office: 679 Days
• Field of Search: 709/245, 709/227, 370/401
• US Class Current: 709/245
• CPC Class Codes: H04L 61/4511 using domain name system [DNS]

Abstract

A gateway is provided which resolves a DNS request in a manner that minimizes the time and bandwidth required to conduct a DNS search as well as increases the chances that a DNS request will be answered for systems in which the gateway is connected to more than one network simultaneously. The gateway performs this by: comparing the domain name query of the DNS request to the domain name of each accessible network; altering the DNS request so that the destination address of the DNS request corresponds to a DNS server within the first matching accessible network, if an accessible network is found whose domain name matches the domain name query; forwarding the DNS request to the first matching accessible network if an accessible network is found whose domain name matches the domain name query; and either forwarding the unaltered DNS request to a network specified by a user if none of the domain names of the accessible networks match the domain name query of the DNS request or forwarding the unaltered DNS request to the largest accessible network unaltered if none of the domain names of the accessible networks match the domain name query of the DNS request.

Claims

1. A method for resolving a Domain Name Service (DNS) request having a domain name query and a destination address in a gateway with more than one accessible network, each accessible network having a domain name, the method comprising:

comparing the domain name query of said DNS request to the domain name of at least one accessible network;

altering the destination address of said DNS request to correspond with a DNS server within a matching accessible network when an accessible network is found whose domain name matches said domain name query;

forwarding said DNS request to said matching accessible network when said matching accessible network is found; and

forwarding the unaltered DNS request to a default network when no matching accessible network is found.

2. The method of claim 1, further comprising examining the domain name query contained within said DNS request.

3. The method of claim 1 wherein said comparing comprises traversing a list of accessible networks, said list also including the domain name of at least one accessible network.

4. The method of claim 3, further comprising ordering said list by size of the accessible networks, with the smallest being first and the largest being last.

5. The method of claim 4 wherein said ordering comprises comparing the network masks of said accessible networks, wherein a smaller network mask indicates a larger network.

6. The method of claim 3 wherein said list further comprises a DNS server address corresponding to said at least one accessible network and said altering comprises altering the DNS request so that the destination address of the DNS packet is the DNS server address corresponding to said matching accessible network from said list.

7. A method for resolving a Domain Name Service (DNS) request having a domain name query and a destination address in a gateway with more than one accessible network, each accessible network having a domain name, the method comprising:

comparing the domain name query of said DNS request to the domain name of at least one accessible network;

altering the destination address of said DNS request to correspond with a DNS server within a matching accessible network when an accessible network is found whose domain name matches said domain name query;

forwarding said DNS request to said matching accessible network when said matching accessible network is found; and

forwarding the unaltered DNS request to the largest accessible network unaltered when no matching accessible network is found.

8. The method of claim 7, further comprising examining the domain name query contained within said DNS request.

9. The method of claim 7 wherein said comparing comprises traversing a list of accessible networks, said list also including the domain name of at least one accessible network.

10. The method of claim 9, further comprising ordering said list by size of the accessible networks, with the smallest being first and the largest being last and said forwarding the DNS request to the largest accessible network comprises forwarding the DNS request to the last network on said list.

11. The method of claim 10 wherein said ordering comprises comparing the network masks of said accessible networks, wherein a smaller network mask indicates a larger network.

12. An apparatus capable of resolving a Domain Name Service (DNS) request having a domain name query and a destination address, the apparatus comprising:

a domain name query comparator capable of receiving a list of currently accessible networks and their corresponding domain names;

a DNS request alterer capable of receiving said list and coupled to said domain name query comparator when a matching accessible network is found whose domain name matches said domain name query; and

a DNS request forwarder coupled to said domain name query comparator when no matching accessible network is found, said DNS request forwarder further coupled to said DNS request alterer when a matching accessible network is found, said DNS request forwarder further coupled to said matching accessible network when said matching accessible network is found, said DNS request forwarder further coupled to a default network when no matching accessible network is found.

13. The apparatus of claim 12, further comprising a user interface coupled to said DNS request forwarder and configured to specify said default network.

14. The apparatus of claim 12, further comprising a DNS request examiner coupled to said domain name query comparator.

15. The apparatus of claim 12 wherein said list is ordered by size of the accessible networks, with the smallest being first and the largest being last.

16. The apparatus of claim 15, further comprising an accessible network orderer.

17. The apparatus of claim 12 wherein said list further comprises a DNS server address corresponding to at least one accessible network.

18. An apparatus capable of resolving a Domain Name Service (DNS) request having a domain name query and a destination address, the apparatus comprising:

a domain name query comparator capable of receiving a list of currently accessible networks and their corresponding domain names;

a DNS request alterer capable of receiving said list and coupled to said domain name query comparator when a matching accessible network is found whose domain name matches said domain name query; and

a DNS request forwarder coupled to said domain name query comparator when no matching accessible network is found, said DNS request forwarder further coupled to said DNS request alterer when a matching accessible network is found, said DNS request forwarder further coupled to said matching accessible network when said matching accessible network is found, said DNS request forwarder further coupled to the largest accessible network when no matching accessible network is found.

19. The apparatus of claim 18, further comprising a DNS request examiner coupled to said domain name query comparator.

20. The apparatus of claim 18 wherein said list is ordered by size of the accessible networks, with the smallest being first and the largest being last.

21. The apparatus of claim 20, further comprising an accessible network orderer.

22. The apparatus of claim 18 wherein said list further comprises a DNS server address corresponding to at least one accessible network.

23. A program storage device readable by a machine, embodying a program of instructions executable by the machine to perform a method to resolve a Domain Name Service (DNS) request having a domain name query and a destination address in a gateway with more than one accessible network, each accessible network having a domain name, said method comprising:

comparing the domain name query of said DNS request to the domain name of at least one accessible network;

altering the destination address of said DNS request to correspond with a DNS server within a matching accessible network when an accessible network is found whose domain name matches said domain name query;

forwarding said DNS request to said matching accessible network when said matching accessible network is found; and

forwarding the unaltered DNS request to a default network when no matching accessible network is found.

24. The program storage device of claim 23 wherein said method further comprises examining the domain name query contained within said DNS request.

25. The program storage device of claim 23 wherein said comparing comprises traversing a list of accessible networks, said list also including the domain name of at least one accessible network.

26. The program storage device of claim 25 wherein said method further comprises ordering said list by size of the accessible networks, with the smallest being first and the largest being last.

27. The program storage device of claim 26 wherein said ordering comprises comparing the network masks of said accessible networks, wherein a smaller network mask indicates a larger network.

28. The program storage device of claim 25 wherein said list further comprises a DNS server address corresponding to said at least one accessible network and said altering comprises altering the DNS request so that the destination address of the DNS packet is the DNS server address corresponding to said matching accessible network from said list.

29. A program storage device readable by a machine, embodying a program of instructions executable by the machine to perform a method to resolve a Domain Name Service (DNS) request having a domain name query and a destination address in a gateway with more than one accessible network, each accessible network having a domain name, said method comprising:

comparing the domain name query of said DNS request to the domain name of at least one accessible network;

altering the destination address of said DNS request to correspond with a DNS server within a matching accessible network when an accessible network is found whose domain name matches said domain name query;

forwarding said DNS request to said matching accessible network when said matching accessible network is found; and

forwarding the unaltered DNS request to the largest accessible network unaltered when no matching accessible network is found.

30. The program storage device of claim 29 wherein said method further comprises examining the domain name query contained within said DNS request.

31. The program storage device of claim 29 wherein said comparing comprises traversing a list of accessible networks, said list also including the domain name of at least one accessible network.

32. The program storage device of claim 31 wherein said method further comprises ordering said list by size of the accessible networks, with the smallest being first and the largest being last and said forwarding the DNS request to the largest accessible network comprises forwarding the DNS request to the last network on said list.

33. The program storage device of claim 32 wherein said ordering comprises comparing the network masks of said accessible networks, wherein a smaller network mask indicates a larger network.

34. An apparatus for resolving a Domain Name Service (DNS) request having a domain name query and a destination address in a gateway with more than one accessible network, each accessible network having a domain name, the apparatus comprising:

means for comparing the domain name query of said DNS request to the domain name of at least one accessible network;

means for altering the destination address of said DNS request to correspond with a DNS server within a matching accessible network when an accessible network is found whose domain name matches said domain name query;

means for forwarding said DNS request to said matching accessible network when said matching accessible network is found; and

means for forwarding the unaltered DNS request to a default network when no matching accessible network is found.

35. The apparatus of claim 34, further comprising means for examining the domain name query contained within said DNS request.

36. The apparatus of claim 34 wherein said means for comparing comprises means for traversing a list of accessible networks, said list also including the domain name of at least one accessible network.

37. The apparatus of claim 36, further comprising means for ordering said list by size of the accessible networks, with the smallest being first and the largest being last.

38. The apparatus of claim 37 wherein said means for ordering comprises comparing the network masks of said accessible networks, wherein a smaller network mask indicates a larger network.

39. The apparatus of claim 36 wherein said list further comprises a DNS server address corresponding to said at least one accessible network and said means for altering comprises means for altering the DNS request so that the destination address of the DNS packet is the DNS server address corresponding to said matching accessible network from said list.

40. An apparatus for resolving a Domain Name Service (DNS) request having a domain name query and a destination address in a gateway with more than one accessible network, each accessible network having a domain name, the apparatus comprising:

means for comparing the domain name query of said DNS request to the domain name of at least one accessible network;

means for altering the destination address of said DNS request to correspond with a DNS server within a matching accessible network when an accessible network is found whose domain name matches said domain name query;

means for forwarding said DNS request to said matching accessible network when said matching accessible network is found; and

means for forwarding the unaltered DNS request to the largest accessible network unaltered when no matching accessible network is found.

41. The apparatus of claim 40, further comprising means for examining the domain name query contained within said DNS request.

42. The apparatus of claim 40 wherein said means for comparing comprises means for traversing a list of accessible networks, said list also including the domain name of at least one accessible network.

43. The apparatus of claim 42, further comprising means for ordering said list by size of the accessible networks, with the smallest being first and the largest being last and said means for forwarding the DNS request to the largest accessible network comprises means for forwarding the DNS request to the last network on said list.

44. The apparatus of claim 43 wherein said means for ordering comprises means for comparing the network masks of said accessible networks, wherein a smaller network mask indicates a larger network.