Domain blocklists
Domain blocklist monitoring
Your name against the lists a pi-hole actually loads.
What it is for
Your site is up from every continent, the certificate is fine, DNS answers, and a slice of your visitors gets nothing. Not because anything failed, but because your domain is on a consumer DNS blocklist and the people running pi-hole, AdGuard Home, NextDNS or a router with blocking switched on never reach it.
It is invisible from the inside, which is what makes it worth a monitor. Those visitors see a page that does not load and they leave. Your server logs show fewer requests rather than blocked ones, so there is no error to find, and nothing you own can tell you. This is the same failure as being on an email blocklist, one layer over: there your mail silently stops arriving, here your visitors do.
It happens to ordinary sites, not only to advertising networks. A tracking subdomain on your own domain, an analytics endpoint you host yourself, a name that once belonged to somebody else, or a list maintainer's judgement call: any of them puts you on a file that millions of resolvers load every night.
This one is not checked from our locations either. Each list is fetched once a day, once for everybody watching a domain, and your name is looked up in the file we already hold. A list either has you in it or it does not, so there is nothing another continent could see differently.
What you can set
Everything below is on the form when you add one, on every plan.
- What to check
- A domain or a hostname. Both the name you give and, for a www. name, the domain under it: on these lists www.example.com and example.com are two entries and only one of them may be blocked.
On Starter, Pro and Business. We look once a day, which is as often as the lists change, and it counts as one of your monitors. If your domain appears on one, you hear about it the next morning instead of from a customer who could not reach you.
Questions
What is a pi-hole, and why would it block my site?
A pi-hole is a DNS resolver people run at home that refuses to answer for names on a blocklist, so an advert never loads because the name never resolves. AdGuard Home and NextDNS do the same thing. Your site is on one of those lists if a maintainer decided a name on your domain serves advertising, tracking or worse, and nobody tells you.
Which lists do you check?
StevenBlack's unified hosts list today, which is pi-hole's default adlist and therefore the answer to the question most people are actually asking: am I blocked for somebody who installed this and changed nothing. OISD, the AdGuard DNS filter and Hagezi are the obvious next ones, and each gets added on its own merits rather than to make the number bigger.
Why can I not choose my own lists?
Because every list added is another source of a listing you can do nothing about, and an alert nobody can act on is one people learn to ignore. The lists are curated here for the same reason the email blocklists are: a list that blocks half the internet produces support tickets rather than information.
How do I get removed from one?
Through the list itself, and for every one of these that is an issue or a pull request on a repository rather than a form, which is why the alert links to the right place instead of just naming the list. Expect a conversation rather than a button: these are maintained by people, and they will want to know what the name is for.
What if the listing is correct?
Then we say so rather than implying a mistake was made. A track. or ads. subdomain on your own domain is usually listed on purpose and will stay listed, and that is still worth knowing: it tells you which part of your own site a share of your visitors cannot load, which is the thing you were going to find out from a broken analytics report six months later.
Is this the same as the email blocklist check?
No, and they do not overlap. That one asks fifty DNSBLs whether your sending IP or domain is listed, which is about mail being delivered. This one is about a name resolving at all for a visitor, on lists that are files rather than DNS zones. Different lists, different failure, different fix, and being clean on one says nothing about the other.
Does being listed mean my site is down?
Not for everybody, which is exactly what makes it hard to notice. The site is up and serving normally; what is wrong is that a share of the internet cannot resolve the name. The alert says that rather than reporting an outage, because sending somebody to check their web server would be sending them to the wrong place.
Why not just wait for somebody to tell me my site is blocked?
Somebody will tell you, and for a site with a community around it that is genuinely the fastest way to find out, so this is not the check to buy a plan for on its own. The people who cannot tell you are the ones who matter: a visitor behind a pi-hole or an AdGuard install sees a site that does not load, with no explanation and no way to reach you, and assumes you are broken rather than blocked. Being listed usually follows a shared host, a recycled domain or an ad script you dropped in once, and none of those announce themselves.