It is not recomended to set TTL value to zero, see http://technet.microsoft.com/en-us/library/dd197427(WS.10).aspx :
"In general, never configure the TTL to zero. The difference between a setting of 0 or 60 is minimal to the accuracy of the record, but when the TTL is set to 0, there is a significant impact on DNS server performance because the DNS server is constantly querying for the expired data."