computer science

Not Just Another Bogus List

Not Just Another Bogus List is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Not Just Another Bogus List rather than just read about it. In short: Not Just Another Bogus List (NJABL) was a DNS blacklist. NJABL maintained a list of known and potential spam sources (open mail relays, open proxies, open form to mail HTTP gateways, dynamic IP pools, and direct spammers) for the purpose of being able to tag or refuse e-mail and thereby block spam from certain sources.

Key takeaways

Not Just Another Bogus List belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Not Just Another Bogus List to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Not Just Another Bogus List from memory before moving on to harder problems.

Reference excerpt

Not Just Another Bogus List (NJABL) was a DNS blacklist. NJABL maintained a list of known and potential spam sources (open mail relays, open proxies, open form to mail HTTP gateways, dynamic IP pools, and direct spammers) for the purpose of being able to tag or refuse e-mail and thereby block spam from certain sources. NJABL automatically retests only listed open relays every 90 days.

Overview The Open Proxy IPs portion (only) of NJABL data was used in Spamhaus XBL list NJABL's dynamic IP list originally came from Dynablock but was maintained independently since Dynablock stopped updating December 2003. The SORBS dynamic IP list is also a development from Dynablock, but is more aggressively inclusive than NJABL's version.

Timeline As of March 1, 2013, NJABL was in the process of being shut down. The DNSBL zones were emptied. After "the Internet" has had some time to remove NJABL from server configs, the NS's will be pointed off into unallocated space (192.0.2.0/24 TEST-NET-1) to hopefully make the shutdown obvious to those who were slower to notice. As of April 29, the above-mentioned pointing of the DNSBL NS's into 192.0.2.0/24 had been completed. As of Jan 02/2019, the domain name njabl.org was set to expire and dns servers were switched to tucows autorenew servers which would cause any lookups by servers still not having removed the configuration to have rejections.

In January 2024, the domain was picked up by a domain squatter which activated a wildcard DNS record, and as a result, servers which were still erroneously configured to use NJABL began rejecting all emails.

References

Worked examples

Example 1 — a first encounter with Not Just Another Bogus List

Start with the simplest possible case. Write down what Not Just Another Bogus List claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Not Just Another Bogus List before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Not Just Another Bogus List ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Not Just Another Bogus List

In research: Not Just Another Bogus List appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Not Just Another Bogus List in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Not Just Another Bogus List is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer security procedures, Internet stubs, Spamming, so understanding it makes those chapters shorter.
In everyday life: Look for Not Just Another Bogus List outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Not Just Another Bogus List in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Not Just Another Bogus List means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Not Just Another Bogus List out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Not Just Another Bogus List in simple terms?

Why does Not Just Another Bogus List matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Not Just Another Bogus List?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Not Just Another Bogus List.