Robust domain name resolution

Patent metadata

Field	Value
Publication number	US-10439982-B2
Application number	US-201615047247-A
Country	US
Kind code	B2
Filing date	Feb 18, 2016
Priority date	Apr 23, 2009
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

A recursive DNS nameserver system and related domain name resolution techniques are disclosed. The DNS nameservers utilize a local cache having previously retrieved domain name resolution to avoid recursive resolution processes and the attendant DNS requests. If a matching record is found with a valid (not expired) TTL field, the nameserver returns the cached domain name information to the client. If the TTL for the record in the cache has expired and the nameserver is unable to resolve the domain name information using DNS requests to authoritative servers, the recursive DNS nameserver returns to the cache and accesses the resource record having an expired TTL. The nameserver generates a DNS response to the client device that includes the domain name information from the cached resource record. In various embodiments, subscriber information is utilized to resolve the requested domain name information in accordance with user-defined preferences.

First claim

What is claimed is:

1. A computer-implemented method of processing domain name system requests, comprising:
storing at a recursive nameserver domain name records for a plurality of domain names including a first domain name;
issuing a domain name system (DNS) request for the first domain name to one or more authoritative nameservers associated with the first domain name after said storing;
in response to a failure associated with the DNS request for the first domain name, identifying a subset of the plurality of domain names that are associated with the one or more authoritative nameservers, the subset including the first domain name and at least one additional domain name of the plurality of domain names;
in response to the failure associated with the DNS request for the first domain name, modifying the domain name records at the recursive nameserver for the subset of domain names to indicate that the domain name records at the recursive nameserver for the subset of domain names are not to be deleted; and
in response to receiving a reply to a DNS request for a second domain name of the subset of domain names, modifying the domain name records at the recursive nameserver for the subset of domain names to indicate that the domain name records at the recursive nameserver for the subset of domain names are to be deleted.

2. The computer-implemented method of claim 1 , further comprising:
issuing the DNS request for the second domain name to the one or more authoritative nameservers after modifying the domain name records for the subset of domain names; and
receiving the reply to the DNS request for the second domain name.

3. The computer-implemented method of claim 1 , wherein modifying the domain name records at the recursive nameserver for the subset of domain names to indicate that the domain name records at the recursive nameserver for the subset of domain names are not to be deleted includes setting a flag indicating that the domain name records are not to be overwritten.

4. The computer-implemented method of claim 1 , further comprising:
identifying the failure associated with the DNS request for the first domain name in response to failing to receive a response from the one or more authoritative nameservers for the DNS request for the first domain name.

5. The computer-implemented method of claim 1 , further comprising:
identifying the failure associated with the DNS request for the first domain name in response to a server failure response from the one or more authoritative nameservers.

6. The computer-implemented method of claim 1 , wherein:
storing the domain name records includes applying a first hashing algorithm to at least a portion of domain name information for the first domain name; and
modifying the domain name records at the recursive nameserver for the subset of domain names to indicate that the domain name records at the recursive nameserver for the subset of domain names are not to be deleted includes applying a second hashing algorithm to the at least a portion of the domain name information.

7. A system for processing domain name system requests, comprising:
a cache configured to store domain name information including a first domain name for a domain and a second domain name; and
one or more processors in communication with the cache, the one or more processors configured to issue a domain name system (DNS) request to one or more authoritative nameservers for the first domain name and the second domain name, identify the first domain name and the second domain name and modify the domain name information at the cache to indicate that the domain name information for the first domain name and the second domain name is not to be deleted in response to a failure to receive a response to the DNS request from the one or more authoritative nameservers for the first domain name, and modify the domain name information at the cache to indicate that the domain name information is to be deleted in response to receiving a response to a DNS request from the one or more authoritative nameservers for the second domain name.

8. The system of claim 7 , wherein:
the one or more processors are configured to modify the domain name information for the second domain name at the cache to indicate that the domain name information for the second domain name is not to be deleted in response to the failure to receive a response from the one or more authoritative nameservers for the domain name information for the first domain name.

9. The system of claim 7 , wherein the one or more processors are configured to modify the domain name information for the first domain name at the cache by setting a flag indicating that the domain name information is not to be overwritten.

10. The system of claim 7 , wherein:
the cache is a local cache stored in a cluster of recursive nameservers.

11. The system of claim 10 , wherein:
the cluster of recursive nameservers includes a first nameserver and a second nameserver, the first nameserver stores a first cluster cache segment, and the second nameserver stores a second cluster cache segment.

12. One or more processor readable storage devices having processor readable code stored thereon, the processor readable code for programming one or more processors to perform a method comprising:
storing at a recursive nameserver domain name records for a plurality of domain names including a first domain name;
issuing a domain name system (DNS) request for the first domain name to one or more authoritative nameservers associated with the first domain name after said storing;
in response to a failure associated with the DNS request for the first domain name, identifying a subset of the plurality of domain names that are associated with the one or more authoritative nameservers, the subset including the first domain name and at least one additional domain name of the plurality of domain names;
in response to the failure associated with the DNS request for the first domain name, modifying the domain name records at the recursive nameserver for the subset of domain names to indicate that the domain name records at the recursive nameserver for the subset of domain names are not to be deleted; and
in response to receiving a reply to a DNS request for a second domain name of the subset of domain names, modifying the domain name records at the recursive nameserver for the subset of domain names to indicate that the domain name records at the recursive nameserver for the subset of domain names are to be deleted.

13. The one or more processor readable storage devices of claim 12 , the method further comprising:
issuing the DNS request for the second domain name to the one or more authoritative nameservers after modifying the domain name records for the subset of domain names; and
receiving the reply to the DNS request for the second domain name.

14. The one or more processor readable storage devices of claim 12 , wherein modifying the domain name records at the recursive nameserver for the subset of domain names to indicate that the domain name records at the recursive nameserver for the subset of domain names are not to be deleted includes instructions for setting a flag indicating that the domain name records are not to be overwritten.

15. The one or more processor readable storage devices of claim 12 , the method further comprising:
identifying the failure associated with the DNS request for the first domain name in response to failing to receive a response from the one or more authoritative nameservers for the DNS request for the first domain name.

16. The one

Assignees

• Cisco Tech Inc

Inventors

• Treuhaft Noah
• Ulevitch David
• Damm Michael

Classifications

• H04L61/3025

  Domain name generation or assignment · CPC title

• H04L61/35

  involving non-standard use of addresses for implementing network functionalities, e.g. coding subscription information within the address or functional addressing, i.e. assigning an address to a function · CPC title

• H04L61/6009

  Electricity · mapped topic

• H04L29/12066

  Electricity · mapped topic

• H04L29/12811

  Electricity · mapped topic