Best practice on Application Gateway?

Question

Best practice on Application Gateway?

Handinata Tanudjaja 230

Hi everyone,

We would like to understand more on how to utilize Application Gateway better.

The questions we have are:

How to determine the number of Web Server VMs could be handled by 1 Application Gateway?
How to determine the number of Application Gateways we should have?
How does Application Gateway charge?
How to monitor the Application gateway usage?

Thank you

Ravi Kanth Koppala 3,391 Reputation points Microsoft Employee

2025-04-22T17:22:15.9333333+00:00
It sounds like you're looking for guidance on making the most of Azure Application Gateway. Let's break down your questions one by one:

Determining the Number of Web Server VMs per Application Gateway:

The number of Web Server VMs an Application Gateway can handle depends on several factors, including the size of the Application Gateway, the amount of traffic, and the configuration of your backend. Generally, a Standard_v2 or WAF_v2 SKU scales up with backend pool instances, so you can start with the recommended instance size and increase based on measured load. Azure’s guidelines suggest starting with a 1:5 ratio (1 Application Gateway for every 5 VMs), but this can vary based on your specific use case and performance metrics.

Determining the Number of Application Gateways:

The number of Application Gateways you should have depends on your traffic patterns and the need for redundancy. Factors to consider include your desired availability, the regions where your services are hosted, and if you are using zone-redundant configurations. Monitoring your application performance and health probe results will guide adjustments to the number of Gateways.

Charging for Application Gateway:

Charges for Application Gateway are based on the SKU you choose, the number of configured instances, processed traffic, and any extra features like WAF. The cost structure typically includes:

Base charge for the instance

Charge per processed data (GB)

Additional costs if using Web Application Firewall features. You can find more details on Azure's pricing page here.

Monitoring Application Gateway Usage:

You can monitor Application Gateway usage via Azure Monitor, where you can set up metrics and alerts for various aspects such as throughput, latency, and healthy vs. unhealthy back-end instances. Additionally, consider integrating Application Insights for more granular logging and performance metrics.

I hope this helps you get a clearer picture! If you have more specific details about your setup or traffic needs, feel free to share.
Praveen Bandaru 2,665 Reputation points Microsoft External Staff

2025-04-23T17:07:23.1266667+00:00

Hello Handinata Tanudjaja

Following up to see if the above suggestion was helpful. And, if you have any further query do let us know.

Hope the above answer helps! Please let us know do you have any further queries.

Please do consider to “up-vote” wherever the information provided helps you, this can be beneficial to other community members.
Handinata Tanudjaja 230 Reputation points

2025-04-23T22:03:07.3766667+00:00

Thank you very much for the responses!
Let me digest them first.
Thanks again

Accepted answer

0 additional answers

Your answer

Praveen Bandaru 2,665 Reputation points Microsoft External Staff

2025-04-23T17:07:23.1266667+00:00

Hello Handinata Tanudjaja

Following up to see if the above suggestion was helpful. And, if you have any further query do let us know.

Hope the above answer helps! Please let us know do you have any further queries.

Please do consider to “up-vote” wherever the information provided helps you, this can be beneficial to other community members.
Handinata Tanudjaja 230 Reputation points

2025-04-23T22:03:07.3766667+00:00

Thank you very much for the responses!
Let me digest them first.
Thanks again

Answer 1

Hello Handinata Tanudjaja

I understand that you need some clarification on the Azure Application Gateway configuration and workflow.

1.How to determine the number of Web Server VMs could be handled by 1 Application Gateway?

The number of web server virtual machines (VMs) that an Application Gateway can manage depends on several factors, such as the amount of traffic, the complexity of requests, and the performance of backend servers.

Application Gateway V2 has an autoscaling feature that automatically adjusts the number of server instances based on demand. This ensures that your web application always performs optimally, even during busy times.

Check the Azure Application Gateway v2 reference document.

2.How to determine the number of Application Gateways we should have?

The number of Application Gateways required depends on your workload, how your traffic is distributed, and your redundancy needs. To ensure high availability, it's recommended to deploy at least two instances. Autoscaling can help by automatically adjusting the number of instances based on traffic patterns, ensuring your application always performs optimally. check the Autoscaling for Application Gateway.

3.How does Application Gateway charge?

The charges for using an Application Gateway are mainly based on the amount of data it processes. Additionally, the total cost is influenced by the number of Application Gateway instances you have deployed. Check the Application Gateway pricing document.

4.How to monitor the Application gateway usage?

Azure Monitor provides valuable insights into metrics like request rates, response times, and the health of your backend servers. You can set up alerts to notify you of any anomalies and use diagnostic logs for detailed analysis.

Additionally, tools like Azure Monitor Network Insights offer a comprehensive view of your Application Gateway’s performance, helping you keep everything running smoothly.

Hope the above answer helps! Please let us know do you have any further queries.

Please do consider to “up-vote” wherever the information provided helps you, this can be beneficial to other community members.

Praveen Bandaru 2,665 Reputation points Microsoft External Staff

2025-04-24T19:20:52.41+00:00

Hello Handinata Tanudjaja

Following up to see if the above answer was helpful. If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.

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

If you have any other questions or are still running into more issues, let me know in the "comments" and I would be happy to help you.
Praveen Bandaru 2,665 Reputation points Microsoft External Staff

2025-04-25T18:38:02.5866667+00:00

Hello Handinata Tanudjaja

Following up to see if the above answer was helpful. If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.

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

If you have any other questions or are still running into more issues, let me know in the "comments" and I would be happy to help you.

Share via

Best practice on Application Gateway?

0 additional answers

Your answer