what is the difference between 169.254.169.254 and 168.63.129.16 IP in azure

Hi @Om Yadav

Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.

The IP addresses 169.254.169.254 and 168.63.129.16 in Azure serve different purposes and have distinct functionalities.

• The Ip Address 169.254.169.254 is used for Azure Instance Metadata Service (IMDS)
• This service provides information about the running virtual machine instances that can be used to manage and configure them. It is a reserved IP address that allows virtual machines to query metadata about themselves without needing to go through the public internet.
• For example, on a VM if you want to know about the SKU, storage, and network configurations of the VM, you may run the below command to know about VM metadata details. and the response would be in JSON format.

Invoke-RestMethod -Headers @{"Metadata"="true"} -Method GET -NoProxy -Uri "http://169.254.169.254/metadata/instance?api-version=2021-02-01" | ConvertTo-Json -Depth 64

• Below is the sample response of a VM metadata output of the command
• https://learn.microsoft.com/en-us/azure-stack/user/instance-metadata-service?view=azs-2408#rest-response
• While the Ip address 168.63.129.16 is a Virtual Public ip address used to facilitate communication with Azure Platform Resources.
• It serves multiple purposes as below
• Enables the VM Agent to communicate with the Azure platform to signal that it is in a "Ready" state.
• Enables communication with the DNS virtual server to provide filtered name resolution to the resources (such as VM) that don't have a custom DNS server.
• Enables health probes from Azure Load Balancer to determine the health state of VMs.
• Enables the VM to obtain a dynamic IP address from the DHCP service in Azure.
• If you run a packet capture on a VM which is behind an Azure Load balancer you will see the health probe coming from source Ip address 168.63.129.16.
• • https://learn.microsoft.com/en-us/azure/virtual-network/what-is-ip-address-168-63-129-16#scope-of-ip-address-1686312916

Note: Till now IMDS service is also responded on ip 168.63.129.16 along with 169.254.169.254 but from 1 July 2025 all the IMDS call on IP 168.63.129.16 will be blocked.

Kindly refer the below link -

https://techcommunity.microsoft.com/discussions/compute/azure-imds-instance-metadata-service-calls-to-168-63-129-16-blocked-after-july-1/4355715

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Thanks,

Ujjawal Tyagi

Hi Om Yadav,

Thanks for reaching out to Microsoft Q&A.

IP address 168.63.129.16 is a virtual public IP address that is used to facilitate a communication channel to Azure platform resources. Customers can define any address space for their private virtual network in Azure. Therefore, the Azure platform resources must be presented as a unique public IP address. This virtual public IP address facilitates the following operations:

• Enables the VM Agent to communicate with the Azure platform to signal that it is in a "Ready" state.
• Enables communication with the DNS virtual server to provide filtered name resolution to the resources (such as VM) that don't have a custom DNS server. This filtering makes sure that customers can resolve only the hostnames of their resources.
• Enables health probes from Azure Load Balancer to determine the health state of VMs.
• Enables the VM to obtain a dynamic IP address from the DHCP service in Azure.
• Enables Guest Agent heartbeat messages for the PaaS role.

Reference document- https://learn.microsoft.com/en-us/azure/virtual-network/what-is-ip-address-168-63-129-16

IP address " 169.254.169.254" is related to IMDS (Azure Instance Metadata Service). IMDS is a rest API which is available at nonroutable IP address (169.254.169.254).

When you place virtual machine or virtual machine set instances behind an Azure Standard Load Balancer, you can use IMDS to retrieve metadata related to the load balancer and the instances.

Reference Document- https://learn.microsoft.com/en-us/azure-stack/user/instance-metadata-service?view=azs-2408

Please do not forget to "Accept the answer” and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.