if len(clusterCIDRs) == 0 {
			return nil, fmt.Errorf("Controller: Must specify --cluster-cidr if --allocate-node-cidrs is set")
		}

		for idx, cidr := range clusterCIDRs {
			mask := cidr.Mask
			if maskSize, _ := mask.Size(); maskSize > nodeCIDRMaskSizes[idx] {
				return nil, fmt.Errorf("Controller: Invalid --cluster-cidr, mask size of cluster CIDR must be less than or equal to --node-cidr-mask-size configured for CIDR family")
			}
		}
	}

	}
	begin, end = 0, s.maxCIDRs-1
	cidrMask := cidr.Mask
	maskSize, _ := cidrMask.Size()
	var ipSize int

	if !s.clusterCIDR.Contains(cidr.IP.Mask(s.clusterCIDR.Mask)) && !cidr.Contains(s.clusterCIDR.IP.Mask(cidr.Mask)) {
		return -1, -1, fmt.Errorf("cidr %v is out the range of cluster cidr %v", cidr, s.clusterCIDR)
	}

	if s.clusterMaskSize < maskSize {

		ipSize = net.IPv4len
		if cidr.IP.To4() == nil {