Configure Avi Global Server Load Balancing for active-active DNS across two VCF sites.
Prerequisites
VCF lab environment deployed and operational
Lab Environment
Standard VCF lab environment for Avi Load Balancer 30.x Specialist
Tasks
Task 1 Lab B4: Avi GSLB Across Two VCF 9.0 Instances
Configure Avi Global Server Load Balancing for active-active DNS across two VCF sites.
Step 1
Deploy Avi Controllers in both sites and configure GSLB federation.
Step 2
Create a GSLB service with health monitoring against both local VIPs.
Step 3
Configure algorithms: geo-proximity, weighted round-robin, site persistence.
Step 4
Simulate site failure and validate DNS TTL-based failover.
Step 5
Measure time-to-failover and document RTO in SLA terms.
Validation Gate
Check: Verify lab completion
Expected: Lab exercise completed successfully
Common Errors
GSLB DNS not resolving across VCF Instances due to network segmentation
Fix: GSLB requires Avi Controllers at each site to communicate with each other (port 443) and the DNS VS must be reachable from clients at all sites. If VCF Instances are network-segmented (common in multi-site deployments), ensure firewall rules allow: Controller-to-Controller (443), client-to-DNS-VS (53), SE-to-pool-member (application ports).
Geo-based GSLB not working due to incorrect GeoIP database
Fix: Avi GSLB geo-based routing uses a GeoIP database to map client IP to location. If the database is outdated or the client uses a CDN/proxy, geo-resolution may be incorrect. Verify: Avi GSLB logs show the resolved client location. Update GeoIP database regularly. For CDN-proxied traffic, use DNS client-subnet (EDNS0) for accurate geo-resolution.
GSLB site configured as active but SE is not deployed at that site
Fix: GSLB marks a site as active based on Controller configuration, not SE status. If the site is configured active but the local VS has no SEs, GSLB routes traffic to the site but the VS has no capacity to serve it. Verify SE deployment status at each GSLB site before configuring the site as active.
Final Validation
Lab completed successfully
✓ All steps completed → No errors observed
Cleanup / Restore
• Revert to snapshot if needed
Design Reflection (VCDX)
Multi-site GSLB across VCF Instances demonstrates global application delivery architecture. VCDX panelists test cross-site networking requirements and geo-routing accuracy.
⚠ Known Pitfalls (from Community KB)
Configuring GSLB sites as active without verifying SE deployment — traffic is routed but cannot be served.
Relying on GeoIP for accuracy when clients use CDN proxies — use EDNS0 for correct geo-resolution.
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