This weekend after a restart, it appears that one of our servers (server 2008 r2 sp1) is not longer authenticating to the DC (server 2003). From the server that is not authenticating, I can ping the DC, RDP to the DC, and access network shares from the DC. When I run echo %localhost%, it shows the correct DC. When I run netdom query dc, it says "The specified domain either does not exist or could not be contacted." I have reset the server password using netdom. Still no change. One of the odd things that is happening is when I try to create a new SQL login (this is my sql server), it shows the domain as well as the members when I browse for username. When I select the user, it does not fill the information into the box.

Paul, Can you verify that you still have a DNS Record for the server that is having issues authenticating to the DC? Is the DNS Service running on the server? Is the Workstation Service Running on the server? Do you have any Kerberos error messages? Did someone accidently reset the server's computer object in Active Directory? Did you add/enable a firewall on the system? Check to see if the Windows Advanced Firewall turned itself on. -Brenton

DNS is running on the DC. There is a single DNS record in the DNS service for both the system in question and the DC (and dns is resolving correctly on the system in question). Workstation service is runninng on the server in question. There are no Kerberos error messages. The server's computer object in AD is still present and looks like it has not been changed. The windows firewall is off and no other security software is installed on this system.

Please see if any of the suggestions discussed in similar threads helps Event ID 5719 netlogon errors http://social.technet.microsoft.com/Forums/eu/winserverPN/thread/12e3a226-2eb9-4d44-a035-39d2d8e5ae86 Netlogon error 5719 Windows server 2008 R2 64bit http://social.technet.microsoft.com/Forums/en/windowsserver2008r2general/thread/044e57eb-47a4-4988-92b5-faa68ad58025 Event ID 5719 on Win 2008 R2 server http://social.technet.microsoft.com/Forums/en-US/windowsserver2008r2general/thread/c2f2de57-6577-44e2-a2c7-0e29ee800062/ I do not represent the organisation I work for, all the opinions expressed here are my own. This posting is provided "AS IS" with no warranties or guarantees and confers no rights. - .... .- -. -.- ... --..-- ... .- -. - --- ... ....

All of these fixes did not resolve the issue. Now when I run echo %localhost%, it comes back blank.

Paul, Is the DNS Service running on the server in question (not the DC)? What is the age of the record in DNS? Try running on the server in question: ipconfig /flush DNS arp -d ----------------- When you type ipconfig /all does it respond with the correct DNS Servers in the correct order? Are the DNS Servers listed, the IP of your server running DNS? Is it configured to be something else? --------------- When you type hostname in command line, does it report the proper computer name? Can you ping localhost? --------------- What is the role of the server? How many network interfaces does it have? Sorry for all of these questions, communication issues are difficult to track down without tons of details. -Brenton

Issue resolved. The NIC team was misconfigured. A second IP address was added to the NIC team on the system in question and this was causing intermittant communications issues. Second IP address removed and issue was resolved. Thanks for all the help guys.

Thanks for your sharing with us.