How to Check if a Domain Is Blocked Before You Buy Traffic

To check if a domain is blocked, test it against Google Safe Browsing and against fraud and phishing lists, then confirm that it actually opens: DNS points to the right place, the SSL certificate is valid and the registrar has not put the domain on hold. Do all of this before you send the first paid click, and again whenever traffic suddenly drops.

A flagged domain does not announce itself in your dashboard. Clicks keep getting paid, and visitors see a red warning page and leave. This post explains what the warnings do to a campaign, how to run a check by hand, what else can make a domain fail, and what to do when a domain is flagged.

What a warning does to paid clicks

Browsers that use Safe Browsing data show a full-page warning before the site loads. The visitor has to click through several steps to continue, and almost nobody does. From the ad network's side the click happened and you pay for it. From your side nothing arrived.

Hypothetical example: you buy 1,000 clicks at $0.10, so $100. A domain gets flagged after 200 clicks. The remaining 800 clicks cost $80 and produce no visits on your page. If you check the domain once a day, the loss can be a lot larger than if you find out within the hour. The loss grows with the daily budget and with the time between the flag and your reaction.

Other consequences are harder to measure. The warning can also appear for every link on that domain, including links that were working yesterday, and the ad account owner may see a drop in approved traffic without any clear reason.

What Google Safe Browsing is

Safe Browsing is a service from Google that keeps lists of URLs considered dangerous: pages that host malware, pages that try to steal logins or payment data, and sites with deceptive or harmful downloads. Chrome uses it, and other browsers and apps use the same data. The lists change all the time as new URLs are found and old ones are cleaned.

A listing is about the site, not about you personally. If your domain shares a server with someone else, or an old owner of an expired domain was flagged, the listing can still apply to the domain.

How to check a URL by hand

1. Open Google's public Transparency Report and find the Safe Browsing site status page. It has a field where you can paste a domain or a URL.
2. Type the exact domain you plan to use, including the subdomain if you use one, and run the check.
3. Read the result. It will say whether unsafe content was found, whether the site is partially affected, or whether there is no recent data. "No unsafe content found" means the domain is not listed at the moment of the check.
4. Write down the date. A clean result today says nothing about next week.

A manual check covers one domain at a time. If you rotate through dozens of domains it becomes a chore, which is the reason people either skip it or automate it.

Fraud, phishing and reputation lists

Safe Browsing is the biggest source, but not the only one. There are phishing feeds, spam and malware blocklists, and reputation services used by security software, email providers and some ad networks. Each list has its own rules for adding and removing a domain, and each is owned by a different organisation.

You can run a domain through several public lookup tools, each of which queries one or more of these lists. Results will not always match. A domain can be clean in one and listed in another, so decide in advance which lists matter for your traffic sources and check against those.

Other reasons a domain fails

A domain that is not on any list can still send visitors to an error page. These are the ones that happen most often:

A registrar hold is the one people forget. It often follows a complaint or an unpaid renewal, and the notice goes to the contact email on the domain. Make sure that email is one you read.

Pre-launch checklist

Run through this list for every domain, every time, even for one you used last month.

1. Check the exact domain in the Safe Browsing site status page and note the result and date.
2. Check it in at least one other reputation or phishing lookup that is relevant to your traffic sources.
3. Confirm the A record points to your server and that the answer is the same from two different networks.
4. Open the domain on https in a fresh browser profile and look at the certificate: valid dates and a name that matches the domain.
5. Check the registrar panel: status active, expiry date far enough, contact email correct.
6. Open a test link end to end, from the first URL to the final page, and confirm it loads on a phone as well as on a desktop.
7. For a domain you bought used, look up its history before you trust it. An old owner's problems can remain.
8. Decide where alerts go and who reacts. A check nobody reads is a check that did not happen.

What to do if a domain is flagged

1. Stop sending traffic to it. Pause the campaigns or change the link target so clicks do not land on the warning. Every minute of delay costs budget.
2. Find the cause. The list owner often shows what they found, for example a specific page. Look at the whole site and the server: an old file, an injected script or a page you forgot about can be the reason.
3. Fix it. Remove the problem, not only the page the report names.
4. Request a review from the list owner. Google has a review process for Safe Browsing listings, and other lists have their own forms. Describe what you changed. Review times vary and are decided by the list owner, not by you.
5. Move links to a new domain meanwhile. Keep a prepared, checked and working spare domain. Then you only point the links to it. Do not use a new domain for the same content that caused the problem, as the new one can be listed too.

Keep a record of what happened with each flagged domain: date, cause, fix, review result. After a few cases you will see patterns in what your setup does wrong.

How TDS.SO checks domains

A traffic distribution system sits in front of your destinations, and the domain on your links is the part visitors see first. This is why a TDS is a reasonable place to run these checks. What TDS.SO does:

• You connect your own domains by pointing the A record to your server and adding them as a list. SSL is issued automatically.
• Domains are checked in Google Safe Browsing and in fraud lists when you add them and when you press recheck.
• Each domain keeps a check history, so you can see what the results were and when.
• Flagged or unreachable domains are rejected with a reason when you add them.
• If block alerts are on, new domains are rechecked hourly for their first 20 days, and the Telegram bot notifies you if one gets blocked.
• Domains never switch automatically. You move links to a new domain yourself.

The last point is deliberate. A link that quietly changes its domain can send traffic somewhere you did not check. You get the alert and you decide.

FAQ

How often should I check a domain?

Before launch, and then often during the first weeks, because new domains are the ones most likely to be flagged or to have setup mistakes. After that, daily is a reasonable minimum for a domain that carries paid traffic, and an automatic alert is better than remembering.

Does "no unsafe content found" mean the domain is safe?

It means that Safe Browsing had nothing listed for it at the time of the check. It says nothing about other lists, certificates or DNS, and it can change later.

How long does a review take?

It depends on the list owner and on the case, and no one outside that organisation can promise a time. Plan as if the domain is gone for a while and keep a spare ready.

Can I check a domain before I buy it?

Yes. Run the same checks on the domain and look at its history. A domain that was flagged for a previous owner may still carry a bad reputation.

Is a flagged domain my fault?

Sometimes it comes from a shared server, a compromised site or an earlier owner. Whatever the source, the visitor sees the warning and the click is paid, so the response is the same.

If you want checks and alerts for the domains you run traffic through, see domain monitoring and pricing.