Active Directory Archives - Page 7 of 9

Systems Admin

Troubleshoot “The Specified Server Cannot Perform the Requested Operation” Error (0x3a)

Domain join error 0x3a (The specified server cannot perform the requested operation) is almost always a TCP 389 LDAP connectivity problem dressed up in directory-layer language. This article walks the diagnostic path: confirm DNS and basic reachability, prove TCP 389 with Test-NetConnection, then narrow the block to the workstation host firewall, the DC host firewall, or the network ACL between them. Includes the multi-port sweep (53/88/135/389/445/464/3268), the residual-causes list when port 389 is open (AD DS service, time skew, stale computer object), and the common pitfalls (disabled firewall left off, public DNS resolver, 389-vs-636 confusion).

Systems Admin

Troubleshoot “Your Computer Could Not Be Joined to the Domain” Error

The 'maximum number of computer accounts' error comes from ms-DS-MachineAccountQuota, the domain-wide AD attribute that limits how many machine accounts any single authenticated user can create (default: 10). This article walks the four ways to fix it: delegate Create Computer Objects on the OU (recommended), raise the global quota in ADSI Edit (with caution), use a domain admin account (lazy), or reset/delete a stale computer object that is in the way. Includes the post-change replication step and the common pitfalls (setting the quota to 0, delegating to Authenticated Users, forgetting orphan objects, wrong default OU).

Systems Admin

Troubleshoot On-Premise Active Directory (DNS Edition)

The three most common AD-DNS failure modes and how to fix each: clients pointing at the wrong DNS server (point at a peer DC + loopback, never the DC's own external IP); the AD-integrated zone gone missing (recreate as Primary AD-integrated, restart Netlogon to re-register SRV records, verify with dcdiag /test:dns); and inter-DC replication broken (repadmin /replsummary, /showrepl, /syncall /A /e /P, plus time skew and firewall checks). Includes the four-tool diagnostic kit (nslookup SRV / dcdiag / repadmin / Event Viewer Directory Service) and 7 common pitfalls.

Systems Admin

Clean Up Stale DNS Records with PowerShell

One PowerShell script that walks every Primary forward zone on a DNS server and removes every record (A, NS, SRV, CNAME, PTR) that names or points at a demoted host - in one pass. Covers why scavenging alone doesn't catch them, the manual DNS Manager review (zone Properties Name Servers, DomainDnsZones host records, _msdcs SRV records under sites), the full Remove-DNSRecords.ps1 with -WhatIf-first usage, the trailing-dot trap on SRV/NS data, verification with Resolve-DnsName + dcdiag /test:dns, and 7 common pitfalls (skipped -WhatIf, missed trailing dot, non-Primary zones, reverse zones, scavenging assumptions, downstream-DNS confusion, client caches).

Systems Admin

Change the IP Address of a Domain Controller

Three GUI clicks to set a new IP, four CLI commands (ipconfig /flushdns, /registerdns, nltest /dsregdns, dcdiag /fix) to re-register with DNS, and one downstream-consumer audit afterwards. Walks the pre-flight (second DC, console access not RDP, replication health, downstream-consumers list), the GUI procedure with screenshots, the PowerShell-only equivalent (Remove-NetIPAddress / New-NetIPAddress / Set-DnsClientServerAddress), DNS-pointer trap (don't point at the DC's old IP), the SRV-records-need-nltest /dsregdns trap, and 7 common pitfalls (RDP'd into it, peer DCs caching old IP, stale scavenger window, FSMO concerns).

Systems Admin

Active Directory Security Assessment with Purple Knight

Run Semperis Purple Knight Community against an Active Directory forest to surface Indicators of Exposure (weak crypto, print spooler on DCs, AdminSDHolder drift, kerberoastable accounts, etc.) and produce a graded HTML/PDF report. Walks the download, MotW Unblock-File pre-flight, the wizard's six indicator categories (AD Delegation, Account Security, AD Infra, Group Policy, Kerberos, Hybrid), the Zerologon-skip nuance, the score-grade scale, the remediation-then-rescan loop, and the common pitfalls (running as DA, running on a DC, skipping updates, mass-fixing without reading).

Systems Admin

Remove (Demote) a Domain Controller

Two paths to remove a Domain Controller from Active Directory - graceful demotion via Server Manager (Remove Roles and Features wizard) for an online DC, and manual / forced removal via ADUC delete-from-Domain-Controllers-OU for an offline one. Walks both paths end to end with the actual screenshots. Includes the FSMO transfer pre-flight, the Test-ADDSDomainControllerUninstallation cmdlet, the post-demote AD Sites and Services cleanup, and a one-shot DNS scrub script that removes A/NS/SRV/CNAME records for the demoted DC across every Primary forward zone in one pass.

Systems Admin

Universal Group Membership Caching

How to enable Universal Group Membership Caching (UGMC) on a remote AD site so user logons no longer have to traverse a slow WAN to a Global Catalog. Walks the GUI three-click path (Sites and Services > site > NTDS Site Settings > Properties > Enable UGMC) with the actual screenshots, the Set-ADObject PowerShell equivalent (one bit on the NTDS Site Settings options attribute, 0x20), the design choice between UGMC and a local Global Catalog, the 8-hour cache refresh behaviour, and the common pitfalls (right-clicking the wrong node, first-logon needs the GC, stale cache after Universal Group changes).

Systems Admin

Configure a Domain Controller as a Global Catalog Server

How to add the Global Catalog flag to an existing Domain Controller in Active Directory Sites and Services, and the PowerShell equivalent (one bit on the NTDS Settings options attribute via Set-ADObject). Walks the GUI three-click path, the Set-ADObject cmdlet, post-change verification with Get-ADDomainController IsGlobalCatalog / dsquery server -isgc / repadmin /options / Test-NetConnection on port 3268, the partial-attribute-set replication timing caveat, and the common pitfalls (right-clicking the wrong tree node, leaving only one GC, demoting accidentally).

Systems Admin

Active Directory Health Check with PowerShell

One PowerShell script that wraps dcdiag, Test-Connection, Resolve-DnsName, w32tm, Get-Service, and CIM into a single colored HTML report — one row per Domain Controller, 35 columns of pass/warn/fail per cell. Includes the full Get-ADHealth.ps1 source, what each dcdiag test actually catches (Connectivity, SysVolCheck, KccEvent, FSMOCheck, NCSecDesc, etc.), how to schedule a daily SMTP-emailed run, the MotW / Unblock-File / ExecutionPolicy gotchas, and the green-DNS-red-everything-else fingerprint that means a DC is offline.

Systems Admin

Change Users UPN with PowerShell

Configure your on-premises Active Directory UPNs before syncing to Office 365. Add an alternative UPN suffix in AD Domains and Trusts, then bulk-change every user's UPN with Get-ADForest / Set-ADForest and Get-ADUser / Set-ADUser - either across the whole forest or scoped to a single OU. Verification commands included.

Systems Admin

Check Active Directory Forest and Domain Functional Level

How to read the current Active Directory forest functional level (FFL) and domain functional level (DFL), what each level unlocks, the pre-flight checklist before raising, and how to actually raise it with Set-ADForestMode / Set-ADDomainMode. Includes the schema-version-to-OS table, a decision flow for whether to raise, and the common pitfalls (forgotten DCs, Server 2019/2022 reporting Windows2016Forest, irreversibility).

Tag: Active Directory