How to check if a server IP is blocked by ChatGPT before you buy it

2026-10-02 · data from public, reproducible sources · by One IP

You are about to rent a VPS. You want to run ChatGPT on it, or a browser, or an automation pipeline that calls the API. The provider's sales page says nothing about blocks. The IP looks fine. You pay, you log in, and ChatGPT gives you a Cloudflare challenge that never resolves.

The single most common question I get is "can I know this before I pay?" Yes. Not with a reputation score — those answer a different question. You need to test the specific thing you care about, and you can do it in about two minutes using only the provider's looking-glass or a trial box.

Why a clean reputation score tells you nothing here

Run an IP through any reputation checker and it returns a score. A clean score feels like an answer. It is not — it is an answer to "has this address sent spam," which is a completely different question from "will OpenAI's edge let this address through."

We sampled 360 addresses across 12 VPS providers (dataset published, see link at the end). Addresses with zero listings on every public DNS blocklist were still blocked by ChatGPT. Blacklists and ChatGPT's edge protection are two independent systems that share almost no signal. If you buy because the score was clean, you bought the wrong reassurance.

The three-minute pre-purchase check

Step 1: Get the actual address you would receive

Providers do not hand out IPs before purchase, but most publish a looking-glass or a trial. Use it. You need one concrete address, not a range.

Step 2: Check the classification, not the score

curl -s https://ipinfo.io/<ip>/json | grep -E '"org"|"hosting"'

If org names a datacenter ASN (AS14061 DigitalOcean, AS20473 Vultr, AS25820 IT7 Networks) and hosting is true, this address is identifiable as datacenter by anyone who checks. That is the dominant signal OpenAI's edge uses, and no reputation score will tell you about it.

Step 3: Test the service itself — this is the answer

Skip the proxies. From the box (or a trial), request the actual page:

curl -sI --max-time 15 https://chatgpt.com/ | head -5

Read the result exactly as written:

• 403 with cf-mitigated: challenge — blocked by Cloudflare at the edge. The address category is the problem. Nothing you do to the address fixes this.
• 200 — reachable. Test it again at a different hour; edge policy varies.
• Timeout or connection refused — a network path problem, not a block. Different remedy entirely.
• Other 4xx/5xx — service-side. Not a block.

Do not call all of these "blocked." They have four different causes and four different fixes, and only the first one means the IP is wrong for this job.

Step 4: Ask the community that already tested the range

The address you would get is usually adjacent to ones other people already rented. Search the provider's ASN plus "ChatGPT blocked." LowEndTalk and the provider's own forum are where buyers report this. If a whole /24 or /20 of the ASN reports blocks, that is a property of the provider's space — you will inherit it.

What to do with the result

If it is a 403 challenge: the address category is the problem, and it is not fixable. Change providers or change to a residential-class address. Do not dispute it, do not buy a "clean IP" upgrade from the same provider — same ASN, same outcome.

If it is a timeout: test from another location first. Your own network path can be at fault. Only blame the IP when the timeout reproduces from a second vantage point.

If it is 200: you have what you need. Re-check after you actually start using it, because heavy automated traffic from the address can change the outcome later.

The dataset

The 360-address / 12-provider sample is published as JSON, CC BY 4.0. It contains PTR records, DNSBL hits per address, which /24 each hit sits in, and RDAP data — everything you need to see the pattern that a reputation score hides.

This is the check that should happen *before* the payment, not after. Two minutes, one curl command, and you stop trusting a score that was never answering your question.