About dynamic change of IP address when using ELB


When is the IP address changed when using ELB? Does it change depending on the time such as every 30 minutes? Will it change as the number of accesses increases?

1 Answer

When you create an elastic load balancer, a default level of capacity is allocated and configured. As Elastic Load Balancing sees changes in the traffic profile, it will scale up or down. The time required for Elastic Load Balancing to scale can range from 1 to 7 minutes, depending on the changes in the traffic profile. When Elastic Load Balancing scales, it updates the DNS record with the new list of IP addresses. To ensure that clients are taking advantage of the increased capacity, Elastic Load Balancing uses a TTL setting on the DNS record of 60 seconds. It is critical that you factor this changing DNS record into your tests. If you do not ensure that DNS is re-resolved or use multiple test clients to simulate increased load, the test may continue to hit a single IP address when Elastic Load Balancing has actually allocated many more IP addresses. Because your end users will not all be resolving to that single IP address, your test will not be a realistic sampling of real-world behavior.

Refer: https://aws.amazon.com/articles/best-practices-in-evaluating-elastic-load-balancing/

profile pictureAWS
answered 2 years ago
profile pictureAWS
reviewed 2 years ago
  • thank you. I understand how to update the IP address.

    Do you know how the range of IP addresses to be updated is determined?

  • Thanks for your answer, it provide information for ELB scaling up. However, when the ELB scale down, what happens for revoked IP@ still in DNS cache ? Once they are no more resolved, do they still route to the ELB for some period longer than 60 sec ?

You are not logged in. Log in to post an answer.

A good answer clearly answers the question and provides constructive feedback and encourages professional growth in the question asker.

Guidelines for Answering Questions