Basic Understanding of DNS Blacklists

 It is one of the most efficient ways and spam filtering techniques widely used on mail servers to block unwanted emails for anti-spam countermeasures.

DNS Blacklist are used to publish lists of Internet Protocol (IP) addresses of known spammers, abuses, open relays, proxy servers through the DNS (a.k.a. Domain Name System, Domain Name Server or Domain Name Service) that can be queried by software on the Internet. Once it's configured, it can automatically reject or flag email messages as spam, if the sender's IP address is listed on one or more DNS Blacklists.

Each DNS Blacklist has its own criteria to remove any of the listed IP addresses in their database but in most cases have the same way of interrogating the list. As a subscriber to the DNS Blacklists, it is advised to examine their rules and policies before using them.

How Does It Work?

It uses the DNS to transmit information to check if mails should be accepted or rejected.

For example, server A send mail to server B, server B analyze the server A IP address information and execute query against a list of chosen domain name system blacklist servers. Let's say if server A IP address is "122.252.246.234" append the domain name to become "234.246.252.122.dnsbl.example.com" with octets listed in reverse order. If it resolves, the IP address has been blacklisted or is not, then it isn't blacklisted.

What is the Disadvantage?

Majority of DNS Blacklist services available out there either not bother with maintaining, server goes down frequently or have been retired. You are advised to take a turn on various search engines to find and test out whether or not it will function properly before putting any of the DNS query zone into your list. Also note that some of them contain a higher false positive (email messages believed to be legitimate being filtered as spam) rate than others that may have resulted in innocent IP addresses being blocked accidentally. This may lead to a situation where your mail server will reject mails you would like to receive. The other problem is that you must take the right decisions to accept or reject mail from the sender.

The main purpose of using DNS Blacklist filters is to prevent network resources wasted on unsolicited junk mail traffic. In short, DNS Blacklist can help keep you away from spammers.


Comments

Post a Comment

Popular posts from this blog

Tubed Packaged Goods - What Are the Advantages?

  Tubed packaged goods provide consumers with comprehensive information about the products they're buying. Most manufacturers print their brand name or other relevant information right on the front of the packaging. Other tubed packaging options include a note containing extra information or branding. These tubed goods can also be used as marketing tools to spread the word about the product and increase its sales. Here's a look at a few of the benefits of tubed packaging. First, these goods provide great protection and convenience. Unlike their store counterparts, they're also more cost-effective. Plus, tubed packaged goods are also much more attractive and convenient for customers to open than conventional packaging. In addition to offering great protection and convenience, these packaging options offer a greater selection and are also much cheaper. Most retailers even offer online shopping options for tubed packaging. If you're considering using this packaging option,
Read more

5 Steps to Developing Your Idea Into a Profitable Business

The first step in building a successful business is to develop your idea into a product or service. During the initial development phase, you will want to validate your idea with real customers. You should get honest feedback from this group and re-test your idea on a regular basis. In addition, you should engage in conversations in your industry and talk to other entrepreneurs. Ideas While it may seem that a new invention is a step in the right direction, some  idea for invention   may turn out to be useless. They may solve a need, but may not be attractive to a large audience. Realizing this early on can help you avoid wasting time and effort on something that may not be useful. Instead, consider what other uses your invention could have. When brainstorming for ideas for an invention, try to stay grounded and think of common opportunities that you encounter in daily life. This will help you come up with a more effective solution. It's also helpful to focus on a particular industr
Read more

How to Develop Idea Inventions

  If you have a great idea for a new product but are not sure how to get it to the market, you can get help from experts. Nicole Lininger, a marketing and communications professional, recommends that you devise a social media marketing plan. This can be cost-effective and reach a large audience. She also suggests pursuing a patent to protect your idea. Product ideas A product idea is a concept that describes a new item. It specifies its purpose, features, and design elements. Many product ideas include mechanical components. Product designers work with these designs to create the actual object. Product ideas often target specific problems that people have. For example, a vacuum cleaner that works faster and removes more dust could be an excellent idea. After a person has an idea for a product, the next step is to document that idea. It can be in the form of a description, doodles, or a sketch. It is vital to document the idea if it is to be turned into a business. Product ideas that ar
Read more