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We have an Android app that is periodically sending data to our backend server via url panel-lb-ext.unolo.com.

Sometimes, we have Android devices that are unable to connect to our backend because of a dns lookup failure:

20220701_091732:AppDataRepository:Root cause while running upload task:Unable to resolve host "apollo-lb-ext.unolo.com": No address associated with hostname

This url is configured in AWS Route 53 to point to an application load balancer. The TTL is configured as 60 seconds and I don't have the ability to change that value. Route 53 will want to keep it short so that in case of a failure in any one of the targets, the time duration to pick up a new server is short.

Here is the dig output for reference:

dig a apollo-lb-ext.unolo.com

; <<>> DiG 9.16.1-Ubuntu <<>> a apollo-lb-ext.unolo.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20375 ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 65494 ;; QUESTION SECTION: ;apollo-lb-ext.unolo.com. IN A

;; ANSWER SECTION: apollo-lb-ext.unolo.com. 60 IN A 13.235.199.252 apollo-lb-ext.unolo.com. 60 IN A 3.108.34.182 apollo-lb-ext.unolo.com. 60 IN A 15.206.49.163

;; Query time: 100 msec ;; SERVER: 127.0.0.53#53(127.0.0.53) ;; WHEN: Sat Jul 02 12:58:09 IST 2022 ;; MSG SIZE rcvd: 100

What can I do to reduce the changes of temporary DNS lookup resolution failure on these Android devices? I have listed some thoughts below but I need outside counsel to help me go on the right path:

  • I could try looking to increase the TTL on the DNS record but this would mean that in case of failover then I run the risk of increased failover time.
  • EC2 Load balancers come with something called "Global accelerators" which "Create an accelerator to get static IP addresses that act as a global fixed entry point to your load balancers in a single or multiple AWS Regions". The only reason I would consider using this is that it comes with a static ip address. As inflexible as a static ip address is, I would consider it if it helps stop these DNS errors.

Any other thoughts would be much appreciated.dns

psychosk
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    Welcome to Android Enthusiasts Stack Exchange. Just to clarify, are you looking for a solution with the Android setting, or for the server configuration? If it's the former, then it's on-topic and the community here may be possible to help. Otherwise, server configuration may be more suitable on [su] for a home server, or [sf] if it's an enterprise server. – Andrew T. Jul 03 '22 at 07:18
  • @AndrewT. I am asking for anything that can help. If configuring something on the Android device will help, then I would love to know what that is. I can ask this question on Server Fault as well, clarifying there that I am asking for anything on the server configuration side. – psychosk Jul 04 '22 at 08:27
  • Fair, that was just for clarification on what kind of answers to expect on this community, since the question mentioned about increasing TTL on DNS record and configuring EC2 Load Balancers, which is out of scope and unrelated to Android system. – Andrew T. Jul 04 '22 at 08:35

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