When a Windows machine joins an Active Directory domain, several fundamental changes occur:

# Sample PowerShell to verify domain join changes
Get-ComputerInfo | Select-Object CsDomain, CsPartOfDomain
Get-ChildItem "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Group Policy"

• Security Principals Transformation: The machine account is created in AD's Computers container (or specified OU) with a random 120-character password that automatically rotates every 30 days.
• Authentication Pipeline: The Local Security Authority (LSA) subsystem begins processing both local and domain authentication requests via Kerberos/NTLM.
• Group Policy Infrastructure: Client-side extensions (CSEs) are enabled to process GPOs. The machine starts polling for policy changes every 90 minutes with a 30-minute random offset.

Domain-joined machines maintain cached credentials for offline access:

# Check cached credentials count (default is 10)
reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v CachedLogonsCount

# Force policy processing offline
gpupdate /force /boot /sync

Key offline capabilities:

• Cached Logons: Uses SHA-256 hashed credentials from successful logons (configurable via Interactive Logon: Number of previous logons to cache policy)
• Group Policy Application: Last applied policies remain effective until refresh interval expires (even without connectivity)
• Kerberos Ticket Cache: Valid tickets continue working until their expiration time (typically 10 hours for standard tickets)

Group Policy processing follows these technical stages:

1. Core Processing: Machine retrieves GPT.ini from SYSVOL to determine version numbers
2. Extension Processing: Client-side extensions handle specific policy areas:

   Get-ChildItem HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Group Policy\CSE

3. Resultant Set: Policies merge according to LSDOU (Local, Site, Domain, OU) precedence rules

Essential technical references:

• Microsoft Documentation: Active Directory Domain Services Overview
• Protocol Specifications: [MS-ADTS]: Active Directory Technical Specification
• Tooling Reference: dsquery, nltest, and repadmin command-line utilities

# Verify secure channel status
Test-ComputerSecureChannel -Repair

# Check applied GPOs
gpresult /h report.html /f

# Force Kerberos ticket renewal
klist purge -li 0x3e7

When a Windows machine joins an Active Directory domain, several fundamental changes occur:

# PowerShell example of joining domain
Add-Computer -DomainName "corp.example.com" -Credential (Get-Credential) -Restart

• Computer Account Creation: A new computer object gets created in AD's Computers container (or specified OU)
• Security Principals: The machine becomes a security principal with unique SID
• DNS Records: A new host (A) and pointer (PTR) record register in DNS
• Group Policy Client: The gpsvc service starts applying domain policies
• Authentication Changes: Local SAM database gets supplemented with domain authentication

Domain-joined machines maintain limited functionality when disconnected:

// C# check for domain connectivity
bool isDomainConnected = System.DirectoryServices.ActiveDirectory.Domain.GetComputerDomain() != null;

Cached Credentials: By default, Windows caches the last 10 successful logins (configurable via GPO). Users can authenticate using cached credentials for approximately 30 days.

Group Policy Application: Most policies remain enforced while offline because they're applied during login and periodically refreshed. Exceptions include:

• Policies requiring real-time directory access
• Folder redirection paths pointing to unavailable network locations
• Software installation policies

Key policy processing behaviors:

# View effective policies
gpresult /h report.html /scope computer
gpresult /h report.html /scope user

Computer Configuration: Applies during boot sequence before user login. Requires network connectivity at boot time for initial application.

User Configuration: Applies during user login and periodic background refreshes (default 90-120 minutes).

For comprehensive AD integration:

• Microsoft's Active Directory documentation
• Directory Services programming via System.DirectoryServices
• ADSI and LDAP protocol references

Developers should handle these scenarios:

// C# example for handling offline scenarios
try 
{
    using (var domain = Domain.GetComputerDomain())
    {
        // Online domain operations
    }
}
catch (ActiveDirectoryObjectNotFoundException)
{
    // Fallback to cached credentials mode
    Console.WriteLine("Operating in offline domain mode");
}

Time Synchronization: Kerberos requires time skew <5 minutes. Implement NTP fallback mechanisms.

DNS Resolution: Always implement DNS caching and fallback to NetBIOS name resolution.