PowerShell Clear-DnsClientCache

last modified February 15, 2025

In this article, we will cover the Clear-DnsClientCache cmdlet in PowerShell. This cmdlet clears the contents of the DNS client resolver cache.

DNS Cache basics

The DNS client resolver cache stores DNS query responses locally. This improves performance by reducing DNS lookup times for repeated queries. The cache may contain outdated or incorrect records that need clearing. The Clear-DnsClientCache cmdlet removes all cached DNS entries.

Basic Clear-DnsClientCache usage

The simplest way to use Clear-DnsClientCache is without any parameters. This clears all entries from the DNS client resolver cache. The cmdlet does not produce output by default when successful. Administrator privileges are required to execute this command.

dns1.ps1

Clear-DnsClientCache

This command clears the entire DNS client resolver cache. After execution, subsequent DNS queries will require new lookups. No confirmation is requested.

Verifying the cache is cleared

To verify the cache was cleared, use Get-DnsClientCache before and after. The cache should be empty after running Clear-DnsClientCache. This demonstrates the effect of the clearing operation. You can also check with ipconfig /displaydns in Command Prompt.

dns2.ps1

Get-DnsClientCache
Clear-DnsClientCache
Get-DnsClientCache

The first command shows cached entries, the second clears them, and the third verifies the cache is empty. The second Get-DnsClientCache should return no results.

PS C:\> .\dns2.ps1

Entry                     RecordName                Record Status    Section TimeTo DataLength Data
                                                                             Live
-----                     ----------                ------ ------    ------- ------ --------- ----
example.com               example.com               A      Success   Answer   25805         4 93.184.216.34

PS C:\> Clear-DnsClientCache
PS C:\> Get-DnsClientCache
PS C:\>

Clearing cache with confirmation

To add a confirmation prompt before clearing the cache, use the -Confirm parameter. This is useful in scripts where you want to prevent accidental cache clearing. The user must confirm the action before proceeding. This adds an extra layer of safety.

dns3.ps1

Clear-DnsClientCache -Confirm

This command will prompt for confirmation before clearing the DNS cache. Type 'Y' to proceed or 'N' to cancel. The prompt helps prevent accidental execution.

Clearing cache in a script

When using Clear-DnsClientCache in scripts, you may want to suppress the confirmation prompt. Use the -Force parameter to bypass confirmation. This is useful for automated scripts where user interaction is not desired. Always use caution with this parameter.

dns4.ps1

Clear-DnsClientCache -Force

This command clears the DNS cache without any confirmation prompts. It executes immediately when run. Use this only when absolutely necessary in scripts.

Checking cache size before clearing

You can check the cache size before clearing it to understand the impact. Use Get-DnsClientCache with Measure-Object to count entries. This helps in monitoring and troubleshooting scenarios. The count shows how many records will be removed.

dns5.ps1

$count = (Get-DnsClientCache | Measure-Object).Count
Write-Host "Clearing $count DNS cache entries"
Clear-DnsClientCache

This script first counts the cache entries, displays the count, then clears the cache. The output shows how many records were removed. This provides visibility into the operation.

Source

PowerShell documentation

In this article, we have covered the Clear-DnsClientCache cmdlet in PowerShell.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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