In Azure Load Balancer, the rule that links a frontend IP and port to a backend pool, checked by a health probe. Traffic not covered by a rule is not forwarded.
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Terms in this definition
- Azure Load Balancer
Layer-4 load balancer operating within a region, with zone redundancy on the Standard SKU; it has no WAF, doesn't terminate TLS and can't route by URL.
- Backend pool
Targets of a load balancer, identified by IP address or NIC IP configuration. A pool can't span VNets, and a Standard load balancer won't accept a VM that has a Basic public IP.
- Health probe
A TCP, HTTP or HTTPS check a load balancer uses to decide whether backends are healthy. For an HTTP probe, its path has to return HTTP 200.
Related terms
- Floating IP
Option on a load-balancing rule that leaves the frontend IP as the destination address, letting back ends reuse ports. It does not provide session affinity.
- Inbound NAT rule
Forwards one port on a frontend IP to the NIC of a single VM. No backend pool, load-balancing rule or health probe is needed, but the same frontend port cannot be used by two rules on one frontend IP.