Impossible to unblock some web addresses

[support]

It’s actually not blocked. If you’re requesting content from this domain, it’ll succeed (and there will be a record in the Visited tab).

There’s something wrong with the DNS record for this domain. DNS query reports non-existing domain (NXDOMAIN) after the IP addresses are returned. And the last NXDOMAIN record causes the router to add a failed record in the logs.

$ nslookup s.srvsynd.com 1.1.1.1
Server:         1.1.1.1
Address:        1.1.1.1#53

Non-authoritative answer:
Name:   s.srvsynd.com
Address: 18.204.98.216
Name:   s.srvsynd.com
Address: 18.205.232.214
Name:   s.srvsynd.com
Address: 34.231.4.204
Name:   s.srvsynd.com
Address: 34.236.210.83
Name:   s.srvsynd.com
Address: 34.226.87.209
Name:   s.srvsynd.com
Address: 18.204.190.178
Name:   s.srvsynd.com
Address: 35.168.165.225
Name:   s.srvsynd.com
Address: 18.206.31.91
Name:   s.srvsynd.com
Address: 54.156.10.4
Name:   s.srvsynd.com
Address: 52.54.19.1
** server can't find s.srvsynd.com: NXDOMAIN

[Casino]

Thank you so much.

[Casino]

About your reply here below about that only exception (reply #2081)

Blocked Sites by DNS, but i need them!

When the reason “DNS” for the blocked addresses is present in the Internet Logs, which dns are you referring to?

The DNS in the Access Control, or the DNS in the internet settings?

Because there are some sites that i can’t unblock. For example, when i use my webcam for my business meetings in this pandemic time, i have these sites blocked:

flightproxy-euno-01-teams.cloudapp.net
flightproxy-euno-02-teams.cloudapp.net

other times sites about microsoft teams etc…..

i put “cloudapp.net” in the whitelist but the site can’t be unblocked. The reason is always “DNS”. I tried to change DNS in the access control and in the internet settings too (For example Cloudflare or Google DNS), but that site is always blocked.

Try yourself.

• This reply was modified 4 years, 5 months ago by Casino.

[support]

When a domain is blocked by DNS, it is blocked by the DNS in the Access Control profile.

Unless the domain is whitelisted. For a white listed domain, the DNS lookup falls back to the system DNS service, which is the DNS in Internet Settings (or DNS under the Internet section on the Status page, which is the same).

You’ll get blocked by DNS either because the domain is blocked, or it doesn’t exist. The router cannot tell them apart because the response from the DNS service is the same.

In your example above, the domain flightproxy-euno-01-teams.cloudapp.net doesn’t exist for several DNS services. You can try it here: https://mxtoolbox.com/SuperTool.aspx (select “DNS Lookup” in the orange dropdown). Whitelisting it does not make it available.

The domain flightproxy-euno-02-teams.cloudapp.net should work fine.

[Casino]

Thanks, but if i put “cloudapp.net” in the whitelist, pcwrt blocks it anyway. I have the same behavior with the address “infinity-api.extfans.com”.

I put it in the whitelist but the site is always blocked

That’s the problem.

[support]

@casino By https://mxtoolbox.com/SuperTool.aspx, infinity-api.extfans.com does not exist. So it’s not the router that’s blocking the domain.

When you try flightproxy-euno-02-teams.cloudapp.net, is the error still “DNS”?

[Casino]

Using the webcam, i have “flightproxy-euno-02-teams.cloudapp.net” much times. There are other addresses ending with “cloudapp.net”.

But if i put it (cloudapp.net) in the whiteliest and then i go to visit it, pcwrt blocks it. I can’t unblock it.

Answering your question, yes, if i try “cloudapp” and pcwrt blocks it, the reason is always “DNS”.

Why “infinity-api.extfans.com” does not exist? Why i have it in the internet log? I have it MUCH times and the reason of the block is always “DNS”.

• This reply was modified 4 years, 5 months ago by Casino.

[support]

The domain infinity-api.extfans.com does not exist because no DNS server can resolve the name to an IP address. If you put the domain name in https://mxtoolbox.com/SuperTool.aspx, you’ll see what I mean.

The domain is in the logs because some app in your network was requesting it. But DNS resolution failed. That’s why the router was displaying blocked by DNS.

If you open a command line window and enter “nslookup flightproxy-euno-02-teams.cloudapp.net”, what do you see in the response?

[Casino]

I have:

C:\Windows\System32>nslookup flightproxy-euno-02-teams.cloudapp.net
Server: family-filter-dns.cleanbrowsing.org
Address: 185.228.168.168

Non-authoritative answer:
Nome: flightproxy-euno-02-teams.cloudapp.net
Address: 52.114.76.109

Why the server is Cleanbrowsing? I have Cloudflare in the internet setting and Quad9 in the access Control. This is very strange.

I have only Cleanbrowsing as DNS on Windows, but i know that Access Control override it.

Anyway I don’t think this is the problem, why there is no reason Cleanbrowsing should block cloudapp.

[support]

You got an IP address back. That means the router did not block this domain: flightproxy-euno-02-teams.cloudapp.net.

The other domain you mentioned earlier, flightproxy-euno-01-teams.cloudapp.net, cannot be resolved by any DNS service. The router reported that it was blocked by DNS, but the real reason was that the name was not resolvable. The router did not block that domain either.

Windows reported the DNS server was CleanBrowsing because that’s how you set it up on your PC. Widnows doesn’t know that the DNS was overridden by the router.

[Casino]

Thanks but, at the end, why if i put “cloudapp.net” in the whitelist it’s always blocked? The reason in the internet setting is always DNS.

My steps are:

1) put cloudapp.net in the whitelist
2) type cloudapp.net in the browser, but the address is blocked.

What’s the way to unlock it?

[support]

The domain “cloudapp.net” cannot be resolved either, i.e., it doesn’t have an IP address. The router reports any domain that is either blocked by the DNS or cannot be resolved by the DNS as “blocked with reason DNS”.

You can enter the domain name “cloudapp.net” into the website I mentioned above and see.

[Casino]

thanks, now i understand the situation. Thanks for the explanation.

[Author]

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