if numExhaustedZones >= len(nt.zones) { // all zones are exhausted.
			return nodesList, errors.New("all zones exhausted before reaching count of nodes expected")
		}
		for zoneIndex := 0; zoneIndex < len(nt.zones); zoneIndex++ {
			na := nt.tree[nt.zones[zoneIndex]]
			if nodeIndex >= len(na) { // If the zone is exhausted, continue
				if nodeIndex == len(na) { // If it is the first time the zone is exhausted
					numExhaustedZones++
				}

			errs = AppendValidation(errs, fmt.Errorf("locality lb failover region should not contain '*' wildcard"))
		}
	}

	return
}

const (
	regionIndex int = iota
	zoneIndex
	subZoneIndex
)

func validateLocalities(localities []string) error {
	regionZoneSubZoneMap := map[string]map[string]map[string]bool{}
	for _, locality := range localities {