Gibraltar: Thursday 27 June 2024 at 11:50 CET
THREAT INTEL: What is a DNSBL? – A DNSBL or A DNSBL or Domain Name System Blacklist is a part of a system that ‘helps’ to fight email spammers.
By Andy Jenkinson – Guest Contributor | Group CEO Cybersec Innovation Partners
via IainFRASER.net/CYBERInsights
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A DNSBL or Domain Name System Blacklist is a part of a system that ‘helps’ to fight email spammers. There are a lot of such lists in existence, each of them containing a list of IP addresses known to send spam.
DNS blacklists are used by email services and website admins to effectively keep spam out of their clients’ inboxes. Think of such lists as bouncers, but instead of having a list of people to let in, they contain lists of people to keep out.
Despite its name, the term “list” is an oversimplification. These “blacklists” are not simply lists but rather security mechanisms that utilize various methods of checking whether or not a specific address or domain is listed, gets listed, or is removed from the list. These lists can also sometimes be referred to as “blocklists”.
PDNS is similar in the fact it collects information, retrospectively on known rogue IP addresses used for malicious purposes to block them. Both DNSBL and PDNS are reliant on the information being shared ‘after the event’ and populated into lists.
Neither DNSBL nor PDNS are a substitute to proactive DNS controls and management.
The single IP address below has a total of 9 out of the 24 most popular on the DNSBL. One of those using this provider and the ASN is Gartner. The server is based in Washington DC and also has nearly 30 million IPv4 addresses, over 100,000 domains hosted, 30 adult domains, and 52 Spam hosts.
Still think DNS doesn’t matter …?
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