Correlating nameserver IPv6 and IPv4 addresses

Abstract

Nameserver addresses are correlated in a multi-tier name server hierarchy comprising a first level authority for a domain, and one or more second level authorities to which the first level authority delegates with respect to a particular sub-domain associated with the domain. Preferably, the first level authority is IPv4-based and at least one second level authority is IPv6-based. The first level authority responds to a request issued by a client caching nameserver (a “CCNS”) and returns an answer that includes both IPv4 and IPv6 authorities for the domain. The CCNS is located at an IPv4 source address that is passed along to the first level authority with the CCNS request. The first level authority encodes the CCNS IPv4 source address in the IPv6 destination address of at least one IPv6 authority. Then, when the CCNS then makes a follow-on IPv6 request (with respect to the sub-domain) directed to the IPv6 authority, the IPv6 authority knows both the IPv6 address of the CCNS (as well as its IPv4 address. The IPv6 authority maintains the IPv4-IPv6 correlation. Over time, the IPv6 authority builds up a database of these CCNS IPv6-IPv4 associations.

Having described our invention, what we claim is as follows: 
     
         1 . A method, comprising:
 in response to receipt at a first level authority of a first request for a domain, the first level authority operative within a nameserver hierarchy, the first request including an IPv4 source address of a caching nameserver making the first request, returning to the caching nameserver information identifying at least an IPv6 authority and zero or more IPv4 authorities, where the IPv4 source address of the caching nameserver is encoded in an IPv6 address of the IPv6 authority;   receiving, at the IPv6 authority that is a second level authority within the nameserver hierarchy, a second request, the second request having associated therewith an IPv6 address of the caching nameserver that includes the IPv4 source address of the caching nameserver encoded therein;   at the IPv6 authority, saving, as an IPv4-to-IPv6 correlation, an association between the IPv4 source address of the caching nameserver and the IPv6 address of the caching nameserver; and   thereafter using the saved IPv4-to-IPv6 correlation to provide one of: an answer to an IPv4 nameserver asking for a first record type, and an answer to an IPv6 nameserver asking for a second record type.   
     
     
         2 . The method as described in  claim 1  wherein the first record type is an AAAA record, and the second record type is an A record. 
     
     
         3 . The method as described in  claim 1  further including the IPv6 authority verifying the second request prior to responding to the second request. 
     
     
         4 . The method as described in  claim 1  wherein the IPv4 source address of the CCNS is encoded by placing a 32 bit IPv4 address unmodified in the lowest 32 bits of the IPv6 address. 
     
     
         5 . The method as described in  claim 1  wherein the IPv4 source address of the CCNS is encoded by encrypting the IPv4 address in low-order bits of the IPv6 address. 
     
     
         6 . The method as described in  claim 1  wherein the IPv4 source address of the CCNS is encoded by cryptographically hashing the IPv4 address into low-order bits of the IPv6 address. 
     
     
         7 . The method as described in  claim 1  wherein the IPv6 address of at least one of the IPv6 authorities also includes a digital signature of the IPv4 address or an encoding of the IPv4 address. 
     
     
         8 . An article comprising a non-transitory machine readable medium that stores a program, the program being executed to perform a set of operations comprising:
 in response to receipt at a first level authority of a first request for a domain, the first level authority operative within a nameserver hierarchy, the first request including an IPv4 source address of a caching nameserver making the first request, returning to the caching nameserver information identifying at least an IPv6 authority and zero or more IPv4 authorities, where the IPv4 source address of the caching nameserver is encoded in an IPv6 address of the IPv6 authority;   receiving, at the IPv6 authority that is a second level authority within the nameserver hierarchy, a second request, the second request having associated therewith an IPv6 address of the caching nameserver that includes the IPv4 source address of the caching nameserver encoded therein;   at the IPv6 authority, saving, as an IPv4-to-IPv6 correlation, an association between the IPv4 source address of the caching nameserver and the IPv6 address of the caching nameserver; and   thereafter using the saved IPv4-to-IPv6 correlation to provide one of: an answer to an IPv4 nameserver asking for a first record type, and an answer to an IPv6 nameserver asking for a second record type.   
     
     
         9 . The article as described in  claim 8  wherein the first record type is an AAAA record, and the second record type is an A record. 
     
     
         10 . Apparatus, comprising:
 a processor; and   computer memory holding computer program instructions executed by the processor, the computer program instructions comprising program code configured to:
 in response to receipt at a first level authority of a first request for a domain, the first level authority operative within a nameserver hierarchy, the first request including an IPv4 source address of a caching nameserver making the first request, return to the caching nameserver information identifying at least an IPv6 authority and zero or more IPv4 authorities, where the IPv4 source address of the caching nameserver is encoded in an IPv6 address of the IPv6 authority; 
 receive, at the IPv6 authority that is a second level authority within the nameserver hierarchy, a second request, the second request having associated therewith an IPv6 address of the caching nameserver that includes the IPv4 source address of the caching nameserver encoded therein; 
 at the IPv6 authority, save, as an IPv4-to-IPv6 correlation, an association between the IPv4 source address of the caching nameserver and the IPv6 address of the caching nameserver; and 
 thereafter use the saved IPv4-to-IPv6 correlation to provide one of: an answer to an IPv4 nameserver asking for a first record type, and an answer to an IPv6 nameserver asking for a second record type. 
   
     
     
         11 . The apparatus as described in  claim 10  wherein the first record type is an AAAA record, and the second record type is an A record.