Helllo! We are experiencing intermittent login issues since early August, 2016 for all users from any browser or workstation (location does not seem to be an issue). We have a cross domain - VPN tunnel, which has not experienced recent outages to cause failed logons or AD lookups. Other systems relying on the VPN tunnel are not experiencing authentication issues. Successful manual telnet tests between the Domain Controllers were successful during Jenkins failed logins. We are not ruling out a network issue but we can't see any problems. We have not recently upgraded Jenkins or the Active Directory Plugin.

Looking forward to any help to resolve our issue.

Output from log:

Aug 27, 2016 7:11:51 AM hudson.plugins.active_directory.ActiveDirectoryUnixAuthenticationProvider retrieveUser
WARNING: Credential exception trying to authenticate against ####### domain
org.acegisecurity.BadCredentialsException: Failed to retrieve user information for ##############; nested exception is javax.naming.PartialResultException Root exception is javax.naming.CommunicationException: DomainDnsZones.######## [Root exception is java.net.ConnectException: Connection timed out: connect]
at hudson.plugins.active_directory.ActiveDirectoryUnixAuthenticationProvider$1.call(ActiveDirectoryUnixAuthenticationProvider.java:332)
at hudson.plugins.active_directory.ActiveDirectoryUnixAuthenticationProvider$1.call(ActiveDirectoryUnixAuthenticationProvider.java:235)
at com.google.common.cache.LocalCache$LocalManualCache$1.load(LocalCache.java:4767)
at com.google.common.cache.LocalCache$LoadingValueReference.loadFuture(LocalCache.java:3568)
at com.google.common.cache.LocalCache$Segment.loadSync(LocalCache.java:2350)
at com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2313)
at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2228)
at com.google.common.cache.LocalCache.get(LocalCache.java:3965)
at com.google.common.cache.LocalCache$LocalManualCache.get(LocalCache.java:4764)
at hudson.plugins.active_directory.ActiveDirectoryUnixAuthenticationProvider.retrieveUser(ActiveDirectoryUnixAuthenticationProvider.java:235)
at hudson.plugins.active_directory.ActiveDirectoryUnixAuthenticationProvider.retrieveUser(ActiveDirectoryUnixAuthenticationProvider.java:200)
at hudson.plugins.active_directory.ActiveDirectoryUnixAuthenticationProvider.retrieveUser(ActiveDirectoryUnixAuthenticationProvider.java:142)
at org.acegisecurity.providers.dao.AbstractUserDetailsAuthenticationProvider.authenticate(AbstractUserDetailsAuthenticationProvider.java:122)
at org.acegisecurity.providers.ProviderManager.doAuthentication(ProviderManager.java:200)
at org.acegisecurity.AbstractAuthenticationManager.authenticate(AbstractAuthenticationManager.java:47)
at org.acegisecurity.ui.webapp.AuthenticationProcessingFilter.attemptAuthentication(AuthenticationProcessingFilter.java:74)
at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:252)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at jenkins.security.BasicHeaderProcessor.doFilter(BasicHeaderProcessor.java:93)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:249)
at hudson.security.HttpSessionContextIntegrationFilter2.doFilter(HttpSessionContextIntegrationFilter2.java:67)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:76)
at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:171)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1482)
at org.kohsuke.stapler.compression.CompressionFilter.doFilter(CompressionFilter.java:49)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1482)
at hudson.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:81)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1482)
at org.kohsuke.stapler.DiagnosticThreadNameFilter.doFilter(DiagnosticThreadNameFilter.java:30)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1474)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:499)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137)
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:533)
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1086)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:428)
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1020)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
at org.eclipse.jetty.server.Server.handle(Server.java:370)
at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:489)
at org.eclipse.jetty.server.AbstractHttpConnection.content(AbstractHttpConnection.java:960)
at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.content(AbstractHttpConnection.java:1021)
at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:865)
at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:240)
at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)
at org.eclipse.jetty.io.nio.SslConnection.handle(SslConnection.java:196)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:668)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)
at winstone.BoundedExecutorService$1.run(BoundedExecutorService.java:77)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: javax.naming.PartialResultException Root exception is javax.naming.CommunicationException: DomainDnsZones.####### [Root exception is java.net.ConnectException: Connection timed out: connect]
at com.sun.jndi.ldap.AbstractLdapNamingEnumeration.hasMoreImpl(Unknown Source)
at com.sun.jndi.ldap.AbstractLdapNamingEnumeration.hasMore(Unknown Source)
at hudson.plugins.active_directory.LDAPSearchBuilder.searchOne(LDAPSearchBuilder.java:86)
at hudson.plugins.active_directory.ActiveDirectoryUnixAuthenticationProvider$1.call(ActiveDirectoryUnixAuthenticationProvider.java:280)
... 55 more