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title: An Attempt to Resolve the DNS Name of a DC in the Domain Being Joined Has Failed
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description: Provides troubleshooting steps to resolve the Domain Name System (DNS) error code 0xa8b when you join a workgroup computer to a domain.
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description: Provides troubleshooting steps for resolving the Domain Name System (DNS) error code 0xa8b when you join a workgroup computer to a domain.
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ms.date: 03/26/2025
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manager: dcscontentpm
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audience: itpro
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appliesto:
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- <a href=https://learn.microsoft.com/windows/release-health/windows-server-release-info target=_blank>Supported versions of Windows Server</a>
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---
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# Error code 0xa8b: "An attempt to resolve the DNS name of a DC in the domain being joined has failed"
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# Error code 0xa8b: An attempt to resolve the DNS name of a DC in the domain being joined has failed
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This article provides troubleshooting steps to resolve the Domain Name System (DNS) error code 0xa8b when you join a workgroup computer to a domain. It includes causes and resolutions for common DNS issues.
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This article provides troubleshooting steps for resolving the Domain Name System (DNS) error code 0xa8b when you join a workgroup computer to a domain. It includes causes and resolutions for common DNS issues.
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When you join a workgroup computer to a domain, you receive the following error message:
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This error occurs for one or more of the following reasons:
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- The workgroup computer that's being joined points to an invalid DNS server.
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- The DNS server that's used by the joining computer is invalid, is missing the required zones, or is missing the required records for the target domain.
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- The workgroup computer being joined points to an invalid DNS server.
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- The DNS server used by the joining computer is invalid, is missing the required zones, or is missing the required records for the target domain.
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- The target Active Directory (AD) domain contains a problematic DNS name.
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- Network problems exist on the workgroup computer, the target domain controller (DC), or the network that's used to connect the client and target DC.
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- Network problems exist on the workgroup computer, the target domain controller (DC), or the network used to connect the client and target DC.
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## Troubleshooting steps
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To resolve this error, follow these steps:
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1. Verify that the computer that's being joined points to valid DNS server IP addresses. Invalid examples include:
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1. Verify that the computer being joined points to valid DNS server IP addresses. Invalid examples include:
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- Invalid Internet Service Provider (ISP)-provided DNS servers
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- ISP-provided DNS servers that don't host the AD domain zone
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- A stale or nonexistent DNS server on the corporate intranet
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- A corporate network DNS server that doesn't host the AD domain zone
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- A corporate network DNS server in an error state that prevents it from loading the `_msdcs.<forest root domain>` or target AD domain zones, or from resolving queries for those zones (Event ID 4521 might be logged)
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- Invalid Internet Service Provider (ISP)-provided DNS servers.
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- ISP-provided DNS servers that don't host the AD domain zone.
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- A stale or nonexistent DNS server on the corporate intranet.
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- A corporate network DNS server that doesn't host the AD domain zone.
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- A corporate network DNS server in an error state that prevents it from loading the `_msdcs.<forest root domain>` or target AD domain zones, or from resolving queries for those zones. Event ID 4521 might be logged.
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2. Verify that all DNS servers that are configured on the client are hosting the required zones and valid records for a DC in the target domain. Check for the following misconfigurations:
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2. Verify that all DNS servers configured on the client host the required zones and valid records for a DC in the target domain. Check for the following misconfigurations:
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-The forward lookup zone for the target AD domain is missing.
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-Forward lookup zone for the target AD domain is missing.
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- The `_msdcs` forward lookup zone is missing.
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- The `_msdcs.<forest root domain>` zone doesn't contain a Lightweight Directory Access Protocol (LDAP) SRV record for a DC in the target domain.
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- The host A record is missing from the target AD domain zone.
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- The host A record exists but contains the wrong IP address for the target DC.
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- The host A record exists but is registered by a network interface that isn't accessible to the client computer.
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- The host A record is present but contains the wrong IP address for the target DC.
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- The host A record is present but is registered by a network interface that isn't accessible to the client computer.
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3. Check for special names in the target AD domain that require other configuration:
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3. Check for special names in the target Active Directory domain that require other configuration:
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- Single-label DNS name. For more information, see [Deployment and operation of Active Directory domains that are configured by using single-label DNS names](deployment-operation-ad-domains.md#how-to-enable-windows-based-clients-to-do-queries-and-dynamic-updates-with-single-label-dns-zones).
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- Disjoint namespace. For more information, see [Event IDs 5788 and 5789 occur on a Windows-based computer](event-ids-5788-5789.md).
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- All numeric top-level domains (TLDs) or TLDs containing numeric characters.
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4. Check for network problems on the workgroup computer, target DC, or the network that connects the computer and the target DC. Check specifically for:
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4. Check for network problems on the workgroup computer, target DC, or the network connecting the computer and the target DC:
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- A broken network adapter on the client computer or the target DC
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- A broken network link
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- A broken Network Interface Card (NIC) on the client computer or the target DC.
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- A broken network link.
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The following tools, and similar tools, are available to run various searches:
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-[Nslookup](/windows-server/administration/windows-commands/nslookup) to verify the availability and content of DNS records from the client end.
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-[Ping](/windows-server/administration/windows-commands/ping) or [tracert](/windows-server/administration/windows-commands/tracert) to check the reachability of IP addresses.
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-[PortQry](../networking/portqry-command-line-port-scanner-v2.md) to try specific DC UDP and TCP server ports. A starting point for DC server ports is to [configure a firewall for AD domains and trusts](config-firewall-for-ad-domains-and-trusts.md).
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You can use tools like [nslookup](/windows-server/administration/windows-commands/nslookup) to verify the availability and content of DNS records from the client end, and use tools like [ping](/windows-server/administration/windows-commands/ping) or [tracert](/windows-server/administration/windows-commands/tracert) to check the reachability of IP addresses. You can use [PortQry](../networking/portqry-command-line-port-scanner-v2.md) to try specific DC UDP and TCP server ports. A starting point for DC server ports is to [Configure a firewall for AD domains and trusts](config-firewall-for-ad-domains-and-trusts.md).
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