The problem occured when a client sending recursive queries in which the DNSSec Ok (DO) and Checking Disabled (CD) flags are set in the header, where is allows attackers to inject fake entries into the name server's cache under certain circumstances name servers which allow recursive queries extract information from the additional section of responses, will the result that specific domains are resolved to incorrect IP addresses (e.g. phishing servers).
Although normal clients do not send queries of this type, it is certainly possible that a piece of malware might be able to manipulate a name server in this way using crafted queries within a corporate network. Users should therefore not hesitate to install updates 9.4.3-P4, 9.5.2-P1 or 9.6.1-P2. Administrators should also check whether servers permit recursive queries from external sources and if necessary block this option. The problem does not occur with authoritative-only name servers.
This is affect with all versions of BIND (9.0.x to 9.6.x). So, get patch for your BIND Networks Server.