Branch office DNS storage and resolution

• US 7,567,582 B2
• Filed: 08/19/2005
• Issued: 07/28/2009
• Est. Priority Date: 08/19/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Westhead, Jeffrey J., Esibov, Levon A., Muggli, Nathan Daniel
• Primary Examiner(s): Ton; Dang T
• Assistant Examiner(s): Zhao; Wei
• Application Number:
  US11/208,166
• Publication Number:
  US 20070041393A1
• Time in Patent Office: 1,439 Days
• Field of Search: 370/428, 370/465, 709/238, 709/227
• US Class Current: 370/428
• CPC Class Codes: H04L 61/4511 using domain name system [DNS]
• CPC Class Codes: H04L 61/58 Caching of addresses or names
• CPC Class Codes: H04L 61/59 using proxies for addressing

Abstract

Maintaining DNS records. A computing network system includes a local Domain Name Service (DNS) server connected to one or more local clients or resources at a local branch office in an enterprise network. The local DNS server advertises to the local clients or resources at the local branch office that the DNS server is authoritative. The DNS server receives record information for the local clients or resources. An attempt is made to forward the record information to an enterprise hub DNS server. The record information is stored persistently in a cache. Storing the record information persistently in cache may be performed selectively or non-selectively. When performed selectively, the record information is stored or not stored depending on some result or other action. For example, the result may be stored or not stored depending on the results of attempting to forward to an enterprise hub DNS server.

Claims

1. In a computing network system that includes a local Domain Name Service (DNS) server connected to one or more local clients or resources at a local branch office in an enterprise network, wherein the local DNS server comprises both a local temporary DNS cache and a local persistent DNS cache, a method of maintaining, in the local persistent DNS cache of the local DNS server, records that can be used to resolve IP addresses for host names of the one or more local clients or resources, wherein resolving the IP addresses for the host names of the one or more local clients or resources occurs at the local DNS server, the method comprising:

the local DNS server advertising to the one or more local clients or resources that the DNS server is authoritative;

the local DNS server receiving local DNS record information from the one or more local clients or resources, wherein the local DNS record information comprises information to resolve the IP addresses for the host names of the one or more local clients or resources;

the local DNS server storing the local DNS record information in the local persistent DNS cache that is maintained by the local DNS server, wherein storing the local DNS record information in the local persistent DNS cache may be performed selectively or non-selectively, and wherein the local persistent DNS cache provides persistent local access to the local DNS record information, such that in the event of a power outage coupled with a loss of connection between the branch office and the enterprise hub DNS server, the local DNS information records that are stored in the local persistent DNS cache remain accessible to the local clients and can be used for IP address resolution even while the branch office is disconnected from the enterprise hub DNS server; and

the local DNS server attempting to forward the local DNS record information to an enterprise hub DNS server.

2. The method of claim 1, wherein the local DNS server storing the record information in the local persistent DNS cache is selectively performed based on a response received as a result of the local DNS server attempting to forward the record information to the enterprise hub DNS server, the method further comprising:

the local DNS server receiving the response attempting to forward the record information to the enterprise hub DNS server.

3. The method of claim 2, wherein the response is a failure response from a communication stack indicating that a connection between the local branch office and the enterprise hub is non-operational, wherein the local DNS server storing the record information in the local persistent DNS cache is selectively performed such that the record information is stored in the local persistent DNS cache, the method further comprising:

the local DNS server flagging the record information with a maximum lifetime after which the record information expires.

4. The method of claim 2, wherein the response is a succeed response from the enterprise hub indicating that the record information has been used to update a record for a client or resource, wherein the local DNS server storing the record information in the local persistent DNS cache is selectively performed such that the record information is stored in the local persistent DNS cache.

5. The method of claim 2, wherein the response is a failure response from the enterprise hub indicating that the record information may not be used to update a record for a client or resource, wherein the local DNS server storing the record information in the local persistent DNS cache is selectively performed such that the record information is not stored in the local persistent DNS cache, the method further comprising:

the local DNS server sending the failure response to a local client or resource that sent the record information received by the local DNS server.

6. The method of claim 1, wherein the local DNS server storing the record information in the local persistent DNS cache is non-selectively performed, the method further comprising:

the local DNS server receiving a response in response to the act of attempting to forward the record information to the enterprise hub DNS server.

7. The method of claim 6, wherein the response is a failure response from the enterprise hub indicating that the record information may not be used to update a record for a client or resource, the method further comprising:

the local DNS server invalidating the record information stored in the local persistent DNS cache; and

the local DNS server sending the failure response to a local client or resource that sent the record information received in the act of receiving record information for the one or more local clients or resources.

8. The method of claim 6, wherein the response is a failure response from a communication stack indicating that a connection between the local branch office and the enterprise hub is non-operational, the method further comprising:

the local DNS server flagging the record information with a maximum lifetime after which the record information expires.

9. The method of claim 1, wherein the record information includes an IP address.

10. The method of claim 1, wherein the local DNS server and the enterprise hub are in a common domain namespace.

11. The method of claim 1, further comprising the local DNS server caching remote DNS records for remote names when a connection between the local branch office and the enterprise hub is operational.

12. At least one computer-readable storage medium having thereon stored computer-executable instructions that, when executed by one or more processors of a computing system, cause the computing system to perform the method recited in claim 1.

20. The method of claim 1, wherein, in addition to the local DNS server receiving the local DNS record information from the one or more local clients or resources and storing the local DNS record information in the local persistent DNS cache, the method further comprises:

the local DNS server receiving DNS record information from the enterprise hub DNS server corresponding to DNS record information for clients or resources located outside the branch office, and

the local DNS server storing the DNS record information corresponding to the clients or the resources located outside the branch office in the temporary DNS cache such that it can be retrieved by the local clients or resources for resolution of lip addresses for host names of the clients or resources located outside the branch office.

21. The method of claim 1, further comprising:

the local DNS server receiving a request from the one of the local clients or resources, the request comprising a query that includes a host name;

the local DNS server checking the local persistent DNS cache to determine if a local DNS record exists to resolve an IP address for the host name, and

wherein if the local DNS record exists in the local persistent DNS cache to resolve an IP address for the host name, the local DNS server sending the IP address to the one of the local clients or resources; and

wherein if a local record does not exist in the local persistent DNS cache to resolve an IP address for the host name, the local DNS server checking the local temporary DNS cache to determine if a record exists to resolve the IP address for the host name; and

wherein if the record exists in the local temporary DNS cache to resolve the IP address for the host name, the local DNS server sending the IP address to the one of the local clients or resources, wherein the local temporary DNS cache includes records for clients or resources outside of the local branch office; and

wherein if a local record does not exist in the local persistent DNS cache or the local temporary DNS cache to resolve the IP address for the host name, the local DNS server attempting to query the enterprise hub DNS server to resolve the IP address.

13. A system for storing local DNS record information for clients or resources in a local branch office of an enterprise network, the system comprising:

a branch office, wherein the branch office comprises;

a branch Domain Name Service (DNS) server, the branch DNS server comprising a persistent DNS cache of the local DNS record information for one or more local clients or resources associated with the branch office and a temporary DNS cache of DNS record information for clients or resources located outside the branch office, wherein the local DNS record information comprises information to resolve IP addresses for host names of the one or more local clients or resources, and wherein the persistent DNS cache provides persistent local access to the local DNS record information, such that in the event of a power outage coupled with a loss of connection between the branch office and an enterprise hub, the local DNS information records that are stored in the persistent DNS cache remain accessible to local clients and can be used for IP address resolution even while the branch office is disconnected from the enterprise hub;

enterprise network hardware coupled to the branch DNS server and configured to couple to a network to connect the branch office to the enterprise hub;

local network hardware coupled to the branch DNS server and to the one or more local clients or resources; and

computer executable instructions disposed in the branch DNS server that allow the branch DNS server to advertise through the local network hardware to the one or more local clients or resources that the branch DNS server is authoritative, to receive the local DNS record information for the one or more local clients or resources, to attempt to forward record update data to the enterprise hub, and to maintain the persistent DNS cache of the local DNS record information for the one or more local clients or resources.

14. The system of claim 13, wherein the one or more local clients or resources comprise a file server.

15. The system of claim 13, wherein the one or more local clients or resources comprise a print server.

16. The system of claim 13, wherein the one or more local clients or resources comprise a shared store on a client computer.

17. The system of claim 13, wherein the enterprise network hardware is coupled to a communication stack that is configured to generate a failure message when attempts to forward record information to the enterprise hub cannot be completed because a link between the branch office and the enterprise hub is non-operational.

18. In a computing network system that includes a local Domain Name Service (DNS) server connected to one or more local clients or resources at a local branch office in an enterprise network, a method of resolving host names, the method comprising:

the local DNS server receiving a request from one of the local clients or resources, the request comprising a query that includes a host name;

the local DNS server checking a local persistent DNS cache to determine if a local DNS record exists to resolve an IP address for the host name, and

wherein if the local DNS record exists in the local persistent DNS cache to resolve an IP address for the host name, the local DNS server sending the IP address to the one of the local clients or resources, wherein the local persistent DNS cache includes local DNS records for at least one of the one or more local clients or resources, and wherein the local persistent DNS cache provides persistent local access to the local DNS records, such that in the event of a power outage coupled with a loss of connection between the branch office and an enterprise hub DNS server, the local DNS records that are stored in the local persistent cache remain accessible to the local clients and can be used by the local DNS server for IP address resolution even while the branch is disconnected from the enterprise hub DNS server; and

wherein if a local record does not exist in the local persistent DNS cache to resolve an IP address for the host name, the local DNS server checking a local temporary DNS cache to determine if a record exists to resolve the IP address for the host name; and

wherein if the record exists in the local temporary DNS cache to resolve the IP address for the host name, the local DNS server sending the IP address to the one of the local clients or resources, wherein the local temporary DNS cache includes records for clients or resources outside of the local branch office; and

wherein if a local record does not exist in the local persistent DNS cache or the local temporary DNS cache to resolve the IP address for the host name, the local DNS server attempting to query the enterprise hub DNS server to resolve the IP address.

19. The method of claim 18, further comprising:

the local DNS server receiving record information including the IP address in response to attempting to query an enterprise hub to resolve the IP address;

the local DNS server storing the record information in the local temporary cache; and

the local DNS server sending the IP address to the one of the local clients.