Method and apparatus for domain name service request resolution

• US 6,324,585 B1
• Filed: 11/19/1998
• Issued: 11/27/2001
• 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:
  US09/197,329
• Time in Patent Office: 1,104 Days
• Field of Search: 709/245, 709/203, 709/200, 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 including:

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 said first matching accessible network if an accessible network is found whose domain name matches the domain name query; and

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.

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

3. The method of claim 1, wherein said comparing includes traversing a list of accessible networks, the list also containing the domain name of each accessible network.

4. The method of claim 3, further including 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 includes comparing the network masks of the accessible networks, wherein a smaller network mask indicates a larger network.

6. The method of claim 3, wherein said list further includes a DNS server address corresponding to each accessible network and said altering includes altering the DNS request so that the destination address of the DNS packet is the DNS server address corresponding to said first 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 addressing in a gateway with more than one accessible network, each accessible network having a domain name, the method including:

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

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.

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

9. The method of claim 7, wherein said comparing includes traversing a list of accessible networks, the list also containing the domain name of each accessible network.

10. The method of claim 9, further including 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 includes forwarding the DNS request to the last network on said list.

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

12. A gateway capable of resolving a Domain Name Service (DNS) request having a domain name query and a destination address, the gateway including:

a list of currently accessible networks and their corresponding domain names;

a domain name query comparator coupled to said list;

a DNS request alterer coupled to said list and to said domain name query comparator if an accessible network is found whose domain name matches the domain name query;

a DNS request forwarder coupled to said domain name query comparator if none of the domain names of said accessible networks match the domain name query of the DNS request;

said DNS request forwarder further coupled to said DNS request alterer if an accessible network is found whose domain name matches the domain name query;

said DNS request forwarder further coupled to the first matching network if an accessible network is found whose domain name matches the domain name query;

said DNS request forwarder further coupled to a default network if none of the domain names of said accessible networks match the domain name query of the DNS request.

13. The gateway of claim 12, further including a user interface, said user interface coupled to said DNS request forwarder and specifying said default network.

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

15. The gateway 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 gateway of claim 15, further including an accessible network orderer.

17. The gateway of claim 12, wherein said list further includes a DNS server address corresponding to each accessible network.

18. A gateway capable of resolving a Domain Name Service (DNS) request having a domain name query and a destination address, the gateway including:

a list of currently accessible networks and their corresponding domain names;

a domain name query comparator coupled to said list;

a DNS request alterer coupled to said list and to said domain name query comparator if an accessible network is found whose domain name matches the domain name query;

a DNS request forwarder coupled to said domain name query comparator if none of the domain names of said accessible networks match the domain name query of the DNS request;

said DNS request forwarder further coupled to said DNS request alterer if an accessible network is found whose domain name matches the domain name query;

said DNS request forwarder further coupled to the first matching network if an accessible network is found whose domain name matches the domain name query;

said DNS request forwarder further coupled to the largest accessible network if none of the domain names of said accessible networks match the domain name query of the DNS request.

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

20. The gateway 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 gateway of claim 20, further including an accessible network orderer.

22. The gateway of claim 18, wherein said list further includes a DNS server address corresponding to each accessible network.

23. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps 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, said method steps comprising:

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 said first matching accessible network if an accessible network is found whose domain name matches the domain name query; and

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.

24. The program storage device of claim 23, further including examining the domain name query contained within the DNS request.

25. The program storage device of claim 23, wherein said comparing includes traversing a list of accessible networks, the list also containing the domain name of each accessible network.

26. The program storage device of claim 25, further including 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 includes comparing the network masks of the accessible networks, wherein a smaller network mask indicates a larger network.

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

29. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps 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, said method steps comprising:

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

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.

30. The program storage device of claim 29, further including examining the domain name contained within the DNS request.

31. The program storage device of claim 29, wherein said comparing includes traversing a list of accessible networks, the list also containing the domain name of each accessible network.

32. The program storage device of claim 31, further including 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 includes forwarding the DNS request to the last network on said list.

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