Method and apparatus for detecting incorrect responses to network queries

Abstract

A system that determines if a DNS server suffers from a particular known functional limitation. During operation, the system sends an exploratory query to the DNS server, wherein the exploratory query is specially constructed so as to detect the existence of a functional limitation in the DNS server without causing the DNS server to fail. Next, the system receives an answer to the exploratory query from the DNS server. If the DNS server gives an incorrect response, the system can take actions as may be desired for the implementation. For example, the system may display a message identifying the functional limitation, or the system may establish a mode of operation where it avoids performing those types of DNS queries known to present a risk of crashing the particular Internet gateway.

1 . A method for determining if a domain name system (DNS) server is functionally limited, comprising:
 sending an exploratory query to the DNS server to detect a functional limitation in the DNS server, the functional limitation causing the DNS server to:
 receive the exploratory query, which comprises receiving both a first portion and a second portion of the exploratory query; and 
 based on reading only the first portion of the exploratory query, send a response to the exploratory query; 
   receiving a response to the exploratory query from the DNS server; and   when the response indicates that the functional limitation exists in the DNS server, performing a remedial action.   
     
     
         2 . The method of  claim 1 , wherein the exploratory query comprises “1.0.0.127.dnsbugtest.1.0.0.127.in-addr.arpa.” 
     
     
         3 . The method of  claim 2 , wherein the exploratory query is a “reverse lookup” DNS query that queries a PTR record. 
     
     
         4 . The method of  claim 1 , wherein the exploratory query is configured to detect the functional limitation without at least one of:
 causing the DNS server to fail; and   causing cause the DNS server to communicate with a DNS root name server.   
     
     
         5 . The method of  claim 1 , wherein the method further comprises, when the response does not indicate that a functional limitation exists in the DNS server:
 determining that the DNS server does not have the functional limitation; and   subsequently permitting the sending of DNS queries to the DNS server that the DNS server would not properly read if the DNS server had the functional limitation.   
     
     
         6 . The method of  claim 1 , wherein the DNS server includes at least one of:
 a DNS server;   a DNS cache; or   a DNS relay.   
     
     
         7 . The method of  claim 1 , wherein the remedial action comprises:
 subsequently avoiding sending DNS queries to the DNS server that the DNS server will not properly read due to the functional limitation.   
     
     
         8 . A non-transitory computer-readable storage medium storing instructions that, when executed by a computer, cause the computer to perform a method for determining if a DNS server is functionally limited, the method comprising:
 sending an exploratory query to the DNS server to detect a functional limitation in the DNS server, the functional limitation causing the DNS server to:
 receive the exploratory query, which comprises receiving both a first portion and a second portion of the exploratory query; and 
 based on reading only the first portion of the exploratory query, send a response to the exploratory query; 
   receiving a response to the exploratory query from the DNS server; and   when the response indicates that the functional limitation exists in the DNS server, performing a remedial action.   
     
     
         9 . The computer-readable storage medium of  claim 8 , wherein the exploratory query comprises “1.0.0.127.dnsbugtest.1.0.0.127.in-addr.arpa.” 
     
     
         10 . The computer-readable storage medium of  claim 9 , wherein the exploratory query is a “reverse lookup” DNS query that queries a PTR record. 
     
     
         11 . The computer-readable storage medium of  claim 8 , wherein the exploratory query is configured to detect the functional limitation without at least one of:
 causing the DNS server to fail; and   causing cause the DNS server to communicate with a DNS root name server.   
     
     
         12 . The computer-readable storage medium of  claim 8 , wherein the method further comprises, when the response does not indicate that a functional limitation exists in the DNS server:
 determining that the DNS server does not have the functional limitation; and   subsequently permitting the sending of DNS queries to the DNS server that the DNS server would not properly read if the DNS server had the functional limitation.   
     
     
         13 . The computer-readable storage medium of  claim 8 , wherein the DNS server includes at least one of:
 a DNS server;   a DNS cache; or   a DNS relay.   
     
     
         14 . The computer-readable storage medium of  claim 8 , wherein the remedial action comprises:
 subsequently avoiding sending DNS queries to the DNS server that the DNS server will not properly read due to the functional limitation.   
     
     
         15 . An apparatus that determines if a DNS server is functionally limited, comprising:
 a computer that performs operations for:
 sending an exploratory query to the DNS server to detect a functional limitation in the DNS server, the functional limitation causing the DNS server to:
 receive the exploratory query, which comprises receiving both a first portion and a second portion of the exploratory query; and 
 based on reading only the first portion of the exploratory query, send a response to the exploratory query; 
 
   receiving a response to the exploratory query from the DNS server; and   when the response indicates that the functional limitation exists in the DNS server, performing a remedial action.   
     
     
         16 . The apparatus of  claim 15 , wherein the exploratory query comprises “1.0.0.127.dnsbugtest.1.0.0.127.in-addr.arpa.” 
     
     
         17 . The apparatus of  claim 16 , wherein the exploratory query is a “reverse lookup” DNS query that queries a PTR record. 
     
     
         18 . The apparatus of  claim 15 , wherein the exploratory query is configured to detect the functional limitation without at least one of:
 causing the DNS server to fail; and   causing cause the DNS server to communicate with a DNS root name server.   
     
     
         19 . The apparatus of  claim 15 , wherein the method further comprises, when the response does not indicate that a functional limitation exists in the DNS server:
 determining that the DNS server does not have the functional limitation; and   subsequently permitting the sending of DNS queries to the DNS server that the DNS server would not properly read if the DNS server had the functional limitation.   
     
     
         20 . The apparatus of  claim 15 , wherein the DNS server includes at least one of:
 a DNS server;   a DNS cache; or   a DNS relay.   
     
     
         21 . The apparatus of  claim 15 , wherein the remedial action comprises:
 subsequently avoiding sending DNS queries to the DNS server that the DNS server will not properly read due to the functional limitation.