Why DeepSeek 4.0 keeps giving you
domains that are already taken
We asked DeepSeek 4.0 (deepseek-v4-flash) for 911 "available" .com domains, then checked every single one against the live registry. Most were already owned.
What we tested
Across 24 business categories we asked DeepSeek 4.0 the exact thing a founder types: "give me available .com domain names for a <business>." Then we ran all 911 of its suggestions through the authoritative .com registry in real time. Only 35% were actually free to register.
Same question, wired through Domain Search King's MCP instead:
98.7% verified-available. Because it checks the registry before it answers.
DeepSeek is worst exactly where founders search
The pattern is brutal for professional services. For a tutoring, marketing, or consulting business, almost every name DeepSeek 4.0 called "available" was already gone.
| Business | DeepSeek picks actually free | |
|---|---|---|
| Tutoring service | 2.5% | |
| Marketing agency | 2.6% | |
| Consulting firm | 5% | |
| Law firm | 15% | |
| Accounting firm | 20% | |
| Restaurant | 30% | |
| Coffee shop | 40% | |
| Landscaping business | 67.5% | |
| Roofing company | 77.5% | |
| 👑 Domain Search King verified | 98.7% |
Even DeepSeek's best category (roofing, 77.5%) still hands you a taken domain one time in four. Domain Search King is 98.7% across all of them — because every name is checked against the live registry before it reaches you.
The names it swore were free — owned since the '90s
DeepSeek 4.0 didn't just miss by a little. It confidently offered law-firm names registered around the turn of the millennium — long before the model existed:
| Name DeepSeek called "available" | Registered since |
|---|---|
| litig8.com | 1998 |
| lawvault.com | 1999 |
| jurispro.com | 2000 |
| courtly.com | 2000 |
| lexcounsel.com | 2002 |
| lawbridge.com | 2003 |
| benchmarklaw.com | 2004 |
| bakecrafters.com | 1997 |
Median registration year of DeepSeek's "available" suggestions: 2021. The names that sound available are exactly the ones that sold years ago — the model never knew, because it never checked. Download the full sample (CSV).
It's not just DeepSeek — we tested 10 models. None did the job.
DeepSeek is in good company. Across the same live-verified test, the single best model on earth still got it wrong nearly half the time, and most were far worse. Every one of them hallucinates availability:
| Model | Actually available | |
|---|---|---|
| 👑 Domain Search King MCP · verified | 98.7% | |
| Claude Opus 4.7 best model | 53.1% | |
| Claude Sonnet 5.0 | 35.8% | |
| DeepSeek 4.0 | 35.0% | |
| GPT-5 | 33.9% | |
| Gemini 2.5 Pro | 28.6% | |
| Gemini 3 Flash | 26.0% | |
| Llama 3.1 8B | 22.8% | |
| Mistral Nemo | 20.7% | |
| Hermes 3 70B | 13.6% | |
| Claude Haiku 4.5 | 11.2% |
3,329 suggestions verified live across all models. The full, continuously-updated leaderboard lives on the AI Domain Hallucination Index — the receipts for every number here.
Why every model does this
AI guesses, it doesn't check
DeepSeek 4.0 predicts a plausible-sounding name. It has no connection to the domain registry, so it has no idea whether anyone already owns it.
The good names went years ago
Short, brandable .coms are mostly gone. The names that "sound available" are exactly the ones registered decades ago.
Confidence isn't accuracy
The model states "available" with total confidence — the same way it asserts facts and links it never verified. Sounding sure is not the same as being right.
Verification is a separate step
Availability can only be answered by the registry, in real time. Any tool that skips that step is guessing, no matter how smart the model.
The one-line fix
You don't need a smarter model. You need one that checks. Domain Search King's MCP plugs into Claude, Cursor, or any AI agent and returns only domains verified available against the live registry — 98.7%, not 35%.
Wire in the MCP → Find available domainsSame AI agent, one line of setup. Taken names never reach your screen again.
Already got a name from DeepSeek that came back taken? The 7 moves that fix it.
Methodology
The model
DeepSeek 4.0 (API model deepseek-v4-flash), July 2026. Asked for available .com names across 24 business categories, identical prompt each time.
"Available" = live registry
Every one of the 911 suggestions was checked against the authoritative .com registry in real time. "Available" means the registry returned no active registration at check time — not an estimate.
Reproduce it
Ask DeepSeek for "available" .com names and check each at any registrar. This is the same live check Domain Search King runs before it ever shows you a name.
Part of a living benchmark
This is one model from the AI Domain Hallucination Index, re-run as new models ship. 3,329 suggestions verified across 10 models to date.