Connecting tradingdesk.me

Find out whether you actually use the mailbox

Log in at my.ionos.com → MENU → Email.

• The list is empty → no mailbox exists. The MX records are IONOS defaults that came with the domain. You can relax entirely; copying them across is just good hygiene.
• There is a mailbox listed → mail is live. Follow section 5 exactly and test with a real email afterwards.

Either way, do the copying. It costs two minutes and removes the only thing that can bite you.

Already done — you are on Cloudflare Workers

Your site is live and serving correctly at https://tradingdesk.klubhyde.workers.dev. Confirmed responding HTTP 200 with the academy landing page.

You deployed to Workers rather than Pages. That is fine — it is Cloudflare's recommended route for new projects now, and for a static site like this the two are equivalent. It only changes where the custom-domain button lives, which section 7 accounts for.

Do not point the domain at anything until you have confirmed you can sign in on that address.

Onboard the domain

In the Cloudflare dashboard go to Domains in the left sidebar, then click Onboard a domain (on some accounts this button reads Add a domain).

1. Type tradingdesk.me — just that, no https:// and no www.
2. Choose the option that lets Cloudflare scan for existing DNS records rather than starting empty. This is what copies your mail records across automatically.
3. Click Continue.
4. You are asked to pick a plan. Scroll to Free — $0/month and select it. Do not pick Pro. The Free plan does everything this needs.

Compare Cloudflare's imported records against this list

Go to your new zone → DNS → Records. The scan usually finds everything, but it is not guaranteed to. Confirm all five of these exist, and add any that are missing with Add record:

In Cloudflare, @ means the bare domain and is often displayed as tradingdesk.me. If a field will not accept @, type tradingdesk.me instead.

Delete the two placeholder records

Still on the DNS records page, delete these two if the scan imported them:

These point at the IONOS placeholder page. They have to go, because an A record on the apex conflicts with the record Cloudflare needs to create there in section 7. Leaving them in place is the most common reason people still see the IONOS page after everything else is correct.

Copy Cloudflare's two nameservers

In Cloudflare, open your zone's Overview page. It lists two nameservers assigned to your account — they look like ada.ns.cloudflare.com and lee.ns.cloudflare.com, with names unique to you. Copy both exactly.

Enter them at IONOS

1. Log in at my.ionos.com.
2. Click MENU → Domains & SSL.
3. Find tradingdesk.me in the list and open its settings — click the gear icon in the Actions column, or click the domain itself.
4. Open the Name Server tab.
   This is a different tab from DNS. The DNS tab edits individual records; the Name Server tab is the one that hands control to Cloudflare. If you cannot find the button in the next step, you are on the wrong tab.
5. Click Use custom name servers.
6. Put the first Cloudflare nameserver in Name server 1 and the second in Name server 2. Leave fields 3 and 4 empty — Cloudflare only issues two.
7. Click Save.

IONOS warns you that its DNS zone settings will no longer be used. That is expected and correct — you copied them to Cloudflare in section 5.

Wait for Cloudflare to say Active

Back on the Cloudflare zone Overview, the status reads Pending nameserver update until the change is seen. In practice this is usually under an hour; the official ceiling is 24 hours. Cloudflare emails you when the zone goes Active. Your site and email keep working throughout, because both sets of nameservers are answering with the same records.

Add the custom domain to your Worker

Once the zone is Active: Workers & Pages → Overview → select your tradingdesk Worker → Settings → Domains & Routes → Add → Custom Domain.

Enter tradingdesk.me and select Add Custom Domain.

Cloudflare creates the DNS record and issues the HTTPS certificate for you — you do not touch DNS by hand and you do not manage a certificate. This is also why tradingdesk.me had to become a Cloudflare zone first: Custom Domains require an active zone on the same account.

Add www as well, so both addresses work

You have no www record today, so www.tradingdesk.me currently fails to resolve entirely. Repeat the step above with www.tradingdesk.me — Custom Domains can be added more than once, and your Worker will answer on both.

Set the SSL mode to Full (strict)

In the zone: SSL/TLS → Overview → set the encryption mode to Full (strict).

If this is left on Flexible, you get an endless redirect loop in the browser — ERR_TOO_MANY_REDIRECTS — which looks like a broken site but is only this setting.

Update the URL configuration

Supabase rejects authentication redirects to addresses it does not know. In your Supabase project: Authentication → URL Configuration.

Right now, before the domain is connected

tradingdesk.me still points at IONOS, so an email linking there would be a dead end. Use the Workers address as the Site URL for the moment:

After the custom domain goes live

Change one thing: set Site URL to https://tradingdesk.me. Leave the Redirect URLs exactly as they are — keeping the workers.dev entry means the old address still works, which is useful if the domain ever has trouble.

The /** on the end is a wildcard covering every page and path on that address. Without it you would have to list /reset.html, /app.html and so on individually.

Skip this step and password-reset emails still arrive, but their links silently refuse to sign anyone in. That failure produces no error message, so it is worth getting right the first time.

Six things to confirm

If check 1 still shows the IONOS page after the zone is Active, you almost certainly left the A record from section 5 step 5 in place. Delete it and wait a few minutes.

tradingdesk.me shows the IONOS "This domain is already registered" page

Cause: two things at once.

1. The apex has no record in Cloudflare — no A, no AAAA, no CNAME. Cloudflare's own dashboard says so with its "Visitors cannot reach tradingdesk.me" banner.
2. Your computer still has IONOS's old address (74.208.236.247) in its DNS cache from before the migration, so it keeps going there instead of asking again.

Fix: add the Custom Domain (section 7, step 9), then flush your DNS cache using step C below. Until the Custom Domain exists there is nothing for the apex to point at, so flushing alone will not help — it will just change the error from the IONOS page to "cannot be reached".

www.tradingdesk.me gives ERR_NAME_NOT_RESOLVED

Cause: a cached negative answer, and nothing more. Before the migration, www did not exist, so resolvers recorded "no such name". That memory outlives the change. Right now the two big public resolvers disagree:

The site itself is fine: requested directly at Cloudflare's edge, www returns HTTP 200 with a valid certificate. Only the lookup is stale.

Fix: flush your cache (step C), or simply wait — negative entries expire on their own, typically within the hour. Do not undo anything in Cloudflare because of this error.

The apex still shows the IONOS page after the Custom Domain is added

Cause: a leftover AAAA (IPv6) record. The Custom Domain creates a proxied IPv4 record, but an old IPv6 record from IONOS can survive beside it. Windows prefers IPv6 whenever both exist, so the browser takes the stale address and never tries the good one.

The giveaway is resolvers disagreeing on IPv6 while agreeing on everything else:

That IPv6 address is the one recorded in the section 1 backup, which confirms it is left over rather than something Cloudflare created.

Fix: DNS → Records → find the AAAA row named tradingdesk.me → Delete. Leave the MX, TXT and _dmarc / autodiscover / _domainconnect rows alone — those are email.

Then purge the resolver cache instead of waiting out the 1-hour TTL: open https://one.one.one.one/purge-cache/, enter tradingdesk.me, choose type AAAA, purge, then repeat for type A. Finish with step C below.

Clearing a stale lookup on Windows

1. Close Edge completely — every window.
2. Open Command Prompt (press Start, type cmd) and run:

   ipconfig /flushdns

3. Edge keeps its own cache separately from Windows. Open Edge and go to edge://net-internals/#dns → Clear host cache.
4. Then edge://net-internals/#sockets → Flush socket pools.
5. Reload with Ctrl+Shift+R.

If it still fails, your router or ISP is probably forwarding to Google DNS, which is the resolver currently holding the stale answer. Two ways around it:

• Check from your phone on mobile data — a completely different resolver, and the quickest way to find out whether the problem is yours or the internet's.
• Point your PC at Cloudflare's resolver: Settings → Network & Internet → your Wi-Fi or Ethernet → Edit DNS server assignment → Manual → IPv4 on → Preferred 1.1.1.1, Alternate 1.0.0.1. That resolver already has the correct answer.

Nothing here is permanent. To put everything back exactly as it was:

1. IONOS → Domains & SSL → tradingdesk.me → Name Server tab → Reset DNS or usage. That restores the four original ui-dns nameservers and reactivates the IONOS zone with the records listed in section 1.
2. Propagation back is the same timescale — usually under an hour.
3. Your Worker stays reachable at tradingdesk.klubhyde.workers.dev the whole time, so the academy never goes offline even if you roll the domain back.

1. Push the project to a public GitHub repository.
2. Repository Settings → Pages → set the source branch to main and the folder to / (root).
3. Under Custom domain enter tradingdesk.me → Save.
4. At IONOS → Domains & SSL → tradingdesk.me → DNS tab: delete the existing A record for @ and add these four, all with host @:

   185.199.108.153
   185.199.109.153
   185.199.110.153
   185.199.111.153

5. Back in GitHub, tick Enforce HTTPS. It can take up to 24 hours to become available while the certificate is issued.

Trade-offs: your email is never at risk because the nameservers and all mail records stay untouched at IONOS. In exchange the repository must be public on the free plan, bandwidth has a soft 100 GB/month limit, and you lose Cloudflare's unlimited-bandwidth CDN. For a school-sized audience all three are irrelevant — this is a perfectly good option if the nameserver switch makes you uneasy.