Load balancer is confined to a single Availability Zone
- Severity
- Low
- Service
- Elastic Load Balancing
- Check ID
- ELB_NOT_MULTI_AZ
What this check finds
A load balancer with subnets in only one Availability Zone cannot route traffic if that AZ fails, defeating its purpose as a highly available entry point. Enable at least two Availability Zones so the load balancer survives an AZ outage.
Passing looks like: Load balancer spans multiple Availability Zones.
How to fix it
Add a subnet from a second Availability Zone to the load balancer.
AWS console
EC2 → Load Balancers → select the load balancer → Edit subnets → enable a subnet in another AZ. CLI (ALB/NLB): aws elbv2 set-subnets --load-balancer-arn ARN --subnets SUBNET_AZ_A SUBNET_AZ_B.
Compliance controls it is evidence for
A failing result counts against these controls in KloudLytics; a passing one is evidence towards them. How compliance mapping works
| Framework | Controls |
|---|---|
| NIST SP 800-53 Rev5 (Moderate) |
|
| NIST Cybersecurity Framework 2.0 |
|
| ISO/IEC 27001:2022 Annex A |
|
Checked on every scan
KloudLytics runs this check each time it scans a connected AWS account, through a read-only role, and lists every affected resource with its region. On Pro and Business a fix is written for the specific resource rather than the general case above. The exact access it needs