hello; i have foureexchange 2003 back endand they are sending email directory to intenet; in the server server i have Domain controller and DNS; the DNS forworder to two Public DNS from two different ISP;the forworder like this 1-DNS for the first ISP 2-DNS for second ISP; this configuration same in all my exchange servers; now if the first ISP DNS server does down; two of my exchange server keep sending to internet but another two stop sending to internet tell the Fist server back up again; My question my they are not using the second ISP DNS which are already their DNS forwarder pointing to both of them; can some body help me with this; when the first DNS the two of exchange servers keep giving the below error; but the another servers keep working normally Event Type:ErrorEvent Source:smtpsvcEvent Category:NoneEvent ID:2013Date:7/29/2008Time:5:56:36 AMUser:N/AComputer:DC4Description:SMTP could not connect to any DNS server. Either none are configured, or all are down. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.Data:0000: 7c 26 00 00 |&..

Hi, Please try the following steps: net stop netlogon net stop dns net start dns net start netlogon ipconfig /flushdns ipconfig /registerdns Whats the result? Thanks Allen

i have found missing configuration in two of my exchange servers;which in Default SMTP virual properties; in delivery tab the external DNS option contain only one of my External DNS; i have added the another one; then i have turned off the first one and my exchange keep sending emails out side normally thanks for your idea and help;