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The CBL Index is a ratio between the number of IP addresses in a given IP subnet (Subnetwork) to the number of CBL (Composite Blocking List) listings in the subnet. It may be used to measure how "clean" (of compromised computers) a given subnet is. The higher the number is, the "cleaner" the subnet. The CBL index may be represented in Decibels (dB) or as CIDR suffix ( */xx). Note: other spam researchers prefer to use a percentage of IPs that are listed in a subnet. Using percentages is better suited for "unclean" subnets because "clean" nets have significantly less than 1% of addresses listed. ==Rationale== The CBL DNSBL (Composite Blocking List) lists IP addresses that are compromised by a virus or spam sending infection (computer worm, computer virus, or spamware). The CBL's full zone (data) is available publicly via rsync for download, you are encouraged to register for it - see http://cbl.abuseat.org for more detail. The CBL Index is a reasonably good tool for getting estimates of subnet "outgoing spam reputation". The CBL Index should be treated with caution - subnets often contain IPs with radically different purposes. Assuming all IPs within a subnet represent the same risk/reputation is potentially dangerous. The CBL Index may be used for estimation of overall anti-spam performance of ISP or AS operator. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「CBL Index」の詳細全文を読む スポンサード リンク
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