I have a single Windows 2008 R2 server configured as a domain controller with Active Directory Domain Services and DNS Server. The DNS Server was recently uninstalled and reinstalled in an attempt to fix a (possibly unrelated) problem; the event log was previously flooded with errors (#4000, "The DNS Server was unable to open Active Directory...") which reinstalling did not fix. However, while before it was at least showing and resolving names from the local network (slowly), now it's showing nothing at all. (The original error started with a #4015 error "The DNS server has encountered a critical error from the Active Directory," followed by a long string of #4000 and a few #4004. This may have been caused when a new DNS name was recently added, but I can't be sure of the timing.) Attempting to manage the DNS through Administrative Tools > DNS brings up an error: The server SERVERNAME could not be contacted. The error was: Access was denied. Would you like to add it anyway? Selecting yes just puts a SERVERNAME item on the list, but with all the configuration options grayed out. I attempted editing my hosts file as per this post but to no avail. Running dcdiag, it does identify the home server properly, but fails right away testing connectivity with: Starting test: Connectivity The host blahblahblahyaddayaddayadda could not be resolved to an IP address. Check the DNS server, DHCP, server name, etc. Got error while checking LDAP and RPC connectivity. Please check your firewall settings. ......................... SERVERNAME failed test Connectivity Adding the blahblahblahyaddayaddayadda address to hosts (pointing at 127.0.0.1), the connectivity test succeeded but it didn't seem to solve the fundamental problem (Access was denied) so I hashed it out again. Primary DNS server is properly pointing at 127.0.0.1 according to ipconfig /all. And the DNS server is forwarding requests to external addresses properly (if slowly), but the resolving of local network names is borked. The DNS database itself is small enough that I am (grudgingly) able to rebuild it if need be, but the DNS Server doesn't seem willing to let me work with (or around) it at all. (and yes before you ask there are no system backups available) Where do I go from here? As requested, my (slightly obfuscated) dcdiag output: Directory Server Diagnosis Performing initial setup: Trying to find home server... Home Server = bulgogi * Identified AD Forest. Done gathering initial info. Doing initial required tests Testing server: Obfuscated\BULGOGI Starting test: Connectivity The host a-whole-lot-of-numbers._msdcs.obfuscated.address could not be resolved to an IP address. Check the DNS server, DHCP, server name, etc. Got error while checking LDAP and RPC connectivity. Please check your firewall settings. ......................... BULGOGI failed test Connectivity Doing primary tests Testing server: Obfuscated\BULGOGI Skipping all tests, because server BULGOGI is not responding to directory service requests. Running partition tests on : ForestDnsZones Starting test: CheckSDRefDom ......................... ForestDnsZones passed test CheckSDRefDom Starting test: CrossRefValidation ......................... ForestDnsZones passed test CrossRefValidation Running partition tests on : DomainDnsZones Starting test: CheckSDRefDom ......................... DomainDnsZones passed test CheckSDRefDom Starting test: CrossRefValidation ......................... DomainDnsZones passed test CrossRefValidation Running partition tests on : Schema Starting test: CheckSDRefDom ......................... Schema passed test CheckSDRefDom Starting test: CrossRefValidation ......................... Schema passed test CrossRefValidation Running partition tests on : Configuration Starting test: CheckSDRefDom ......................... Configuration passed test CheckSDRefDom Starting test: CrossRefValidation ......................... Configuration passed test CrossRefValidation Running partition tests on : obfuscated Starting test: CheckSDRefDom ......................... obfuscated passed test CheckSDRefDom Starting test: CrossRefValidation ......................... obfuscated passed test CrossRefValidation Running enterprise tests on : obfuscated.address Starting test: LocatorCheck ......................... obfuscated.address passed test LocatorCheck Starting test: Intersite ......................... obfuscated.address passed test Intersite And my hosts file (minus the hashed lines for brevity): 127.0.0.1 localhost ::1 localhost And, for the sake of completion, here's selected chunks of my netstat -a -n output: TCP 0.0.0.0:88 0.0.0.0:0 LISTENING TCP 0.0.0.0:135 0.0.0.0:0 LISTENING TCP 0.0.0.0:389 0.0.0.0:0 LISTENING TCP 0.0.0.0:445 0.0.0.0:0 LISTENING TCP 0.0.0.0:464 0.0.0.0:0 LISTENING TCP 0.0.0.0:593 0.0.0.0:0 LISTENING TCP 0.0.0.0:636 0.0.0.0:0 LISTENING TCP 0.0.0.0:3268 0.0.0.0:0 LISTENING TCP 0.0.0.0:3269 0.0.0.0:0 LISTENING TCP 0.0.0.0:3389 0.0.0.0:0 LISTENING TCP 0.0.0.0:9389 0.0.0.0:0 LISTENING TCP 0.0.0.0:47001 0.0.0.0:0 LISTENING TCP 0.0.0.0:49152 0.0.0.0:0 LISTENING TCP 0.0.0.0:49153 0.0.0.0:0 LISTENING TCP 0.0.0.0:49154 0.0.0.0:0 LISTENING TCP 0.0.0.0:49155 0.0.0.0:0 LISTENING TCP 0.0.0.0:49157 0.0.0.0:0 LISTENING TCP 0.0.0.0:49158 0.0.0.0:0 LISTENING TCP 0.0.0.0:49164 0.0.0.0:0 LISTENING TCP 0.0.0.0:49178 0.0.0.0:0 LISTENING TCP 0.0.0.0:49179 0.0.0.0:0 LISTENING TCP 0.0.0.0:50480 0.0.0.0:0 LISTENING TCP 127.0.0.1:53 0.0.0.0:0 LISTENING TCP 192.168.12.127:53 0.0.0.0:0 LISTENING TCP 192.168.12.127:139 0.0.0.0:0 LISTENING TCP 192.168.12.127:445 192.168.12.50:51118 ESTABLISHED TCP 192.168.12.127:3389 192.168.12.4:33579 ESTABLISHED TCP 192.168.12.127:3389 192.168.12.100:1115 ESTABLISHED TCP 192.168.12.127:50784 192.168.12.50:49174 ESTABLISHED <snip ipv6> UDP 0.0.0.0:123 *:* UDP 0.0.0.0:500 *:* UDP 0.0.0.0:1645 *:* UDP 0.0.0.0:1645 *:* UDP 0.0.0.0:1646 *:* UDP 0.0.0.0:1646 *:* UDP 0.0.0.0:1812 *:* UDP 0.0.0.0:1812 *:* UDP 0.0.0.0:1813 *:* UDP 0.0.0.0:1813 *:* UDP 0.0.0.0:4500 *:* UDP 0.0.0.0:5355 *:* UDP 0.0.0.0:59638 *:* <snip a few thousand lines> UDP 0.0.0.0:62140 *:* UDP 127.0.0.1:53 *:* UDP 127.0.0.1:49540 *:* UDP 127.0.0.1:49541 *:* UDP 127.0.0.1:53655 *:* UDP 127.0.0.1:54946 *:* UDP 127.0.0.1:58345 *:* UDP 127.0.0.1:63352 *:* UDP 127.0.0.1:63728 *:* UDP 127.0.0.1:63729 *:* UDP 127.0.0.1:64215 *:* UDP 127.0.0.1:64646 *:* UDP 192.168.12.127:53 *:* UDP 192.168.12.127:67 *:* UDP 192.168.12.127:68 *:* UDP 192.168.12.127:88 *:* UDP 192.168.12.127:137 *:* UDP 192.168.12.127:138 *:* UDP 192.168.12.127:389 *:* UDP 192.168.12.127:464 *:* UDP 192.168.12.127:2535 *:* <snip ipv6 again>