> For the complete documentation index, see [llms.txt](https://ajmal-anwar.gitbook.io/zyberspace-by-ajmal/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ajmal-anwar.gitbook.io/zyberspace-by-ajmal/zyberlab/02-active-directory-basics/join-client01-to-domain.md).

# Join CLIENT01 to the Domain

## Objective

Join `CLIENT01` to the `zyberlab.test` Active Directory domain.

This connects the Windows client to the domain so domain users can authenticate on it and the computer can be centrally managed later.

## Requirement

The Windows edition on `CLIENT01` must support joining a traditional Active Directory domain. Windows Pro, Enterprise, and Education editions normally support this. Windows Home does not.

## Step 1 — Configure DNS on CLIENT01

Before joining the domain, `CLIENT01` must use `DC01` for DNS.

On `CLIENT01`:

1. Open **Control Panel**.
2. Go to **Network and Internet** → **Network and Sharing Center**.
3. Select **Change adapter settings**.
4. Right-click the active Ethernet adapter and select **Properties**.
5. Open **Internet Protocol Version 4 (TCP/IPv4)**.
6. Keep the IP address configuration as it is unless you intentionally want a static client address.
7. Set **Preferred DNS server** to the IPv4 address of `DC01`.
8. Select **OK**.

Example only:

```
Preferred DNS server: <DC01 IPv4 address>
```

Do not enter the example address from another guide unless it matches your actual lab.

## Step 2 — Verify DNS

Open Command Prompt and run:

```
ipconfig /all
```

Confirm that the DNS server points to `DC01`.

Then run:

```
nslookup zyberlab.test
```

You should receive a response from the DNS service running on `DC01`.

You can also test the domain controller name:

```
nslookup dc01.zyberlab.test
```

If these fail, fix DNS before trying to join the domain.

## Step 3 — Join the Domain

1. Press **Windows + R**.
2. Enter:

```
sysdm.cpl
```

3. Open the **Computer Name** tab.
4. Select **Change**.
5. Under **Member of**, select **Domain**.
6. Enter:

```
zyberlab.test
```

7. Select **OK**.
8. When prompted, enter credentials for an account allowed to join the computer to the domain. For this first lab, use the domain Administrator account.

Example:

```
ZYBERLAB\Administrator
```

9. After successful authentication, you should see a message similar to:

```
Welcome to the zyberlab.test domain
```

10. Restart `CLIENT01` when prompted.

## Step 4 — Verify the Computer Object

On `DC01`, open **Active Directory Users and Computers**.

By default, `CLIENT01` should appear in the **Computers** container.

For now, leave it there. We will introduce a dedicated workstation OU later when Group Policy labs require it.

## What Happened?

Joining the domain created a computer account in Active Directory and established a trust relationship between `CLIENT01` and the domain.

`CLIENT01` can now use Active Directory for authentication and later receive domain policies.

## Security Relevance

A domain-joined endpoint becomes part of the centralized identity and management environment.

Security teams often monitor domain-join activity, computer-account changes, authentication events, Group Policy changes, and unusual trust failures because they can reveal administrative mistakes or malicious activity.

## Troubleshooting

If you receive **The specified domain either does not exist or could not be contacted**, check DNS first.

Confirm:

```
CLIENT01 DNS → DC01 IPv4 address
```

Then confirm that `CLIENT01` can resolve:

```
dc01.zyberlab.test
zyberlab.test
```

Avoid disabling Windows Firewall or other security controls as a first troubleshooting step.

## Checkpoint

Continue only when:

* `CLIENT01` has restarted
* the domain join completed successfully
* the computer object appears in Active Directory
* `CLIENT01` still uses `DC01` as its DNS server