Issue
When trying to create an application load balancer on aws (up until now I was using the classic ones just fine), I get the following message:
At least two subnets must be specified
Why would an ALB require me to specify two subnets ? Is there any way to create it and use it to LB between instances in a single subnet ?
Solution
So, just to be clear here. @pasmwel basically answered with the docs links but I want to clairfy it since this seems to be getting views.
ALBs require 2 subnets so that, if 1 availability zone goes down, the ALB can still operate on the others.
Which is kinda silly... since AWS could be doing it in the background based on the machine in the target group.
The normal ELB and the TCP LB don't require this for no apparent reason. But if a subnet falls down they will also fail.
Answered By - George Answer Checked By - David Marino (WPSolving Volunteer)