1.1.1.1 randomly stops resoluting domains

Hello,

I was using Cloudflare’s 1.1.1.1 DNS resolver since it first came out, but a while ago I started getting issues with it.

Sometimes, usually around the evening (east Europe) when I try to visit a website, it just simply won’t load up because it can’t resolve the domain name’s IP address. These ‘outages’ usually don’t last long (~10-30 seconds) but they come back a few times.

While the ‘outage’ is ongoing I can ping IP addresses just fine, however using nslookup google.com outputs the following:

DNS request timed out.
    timeout was 2 seconds.
Server:  UnKnown
Address:  1.1.1.1

tracert 1.1.1.1 (normally):

Tracing route to one.one.one.one [1.1.1.1]
over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  192.168.1.1
  2     *        *        *     Request timed out.
  3     4 ms     4 ms     4 ms  213.81.252.23
  4     *        *        *     Request timed out.
  5     4 ms     6 ms     4 ms  62.115.155.166
  6     9 ms     9 ms     9 ms  62.115.119.186
  7     9 ms     9 ms     9 ms  prag-b3-link.telia.net [62.115.136.219]
  8    18 ms    19 ms    18 ms  cloudflare-ic-154352-prag-b3.c.telia.net [80.239.194.86]
  9    15 ms    14 ms    14 ms  one.one.one.one [1.1.1.1]

Trace complete.

tracert 1.1.1.1 (during outage):

Tracing route to one.one.one.one [1.1.1.1]
over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  192.168.1.1
  2     *        *        *     Request timed out.
  3     4 ms     4 ms     4 ms  st-static-bckb-23.213-81-252.telecom.sk [213.81.252.23]
  4     *        *        *     Request timed out.
  5     3 ms     4 ms     4 ms  62.115.155.166
  6     9 ms     9 ms     9 ms  62.115.119.186
  7    15 ms     9 ms    10 ms  prag-b3-link.telia.net [62.115.136.219]
  8    17 ms    19 ms    17 ms  cloudflare-ic-154352-prag-b3.c.telia.net [80.239.194.86]
  9    14 ms    14 ms    14 ms  one.one.one.one [1.1.1.1]

Trace complete.

1.1.1.1 help link (normally):
https://1.1.1.1/help#eyJpc0NmIjoiWWVzIiwiaXNEb3QiOiJObyIsImlzRG9oIjoiTm8iLCJyZXNvbHZlcklwLTEuMS4xLjEiOiJZZXMiLCJyZXNvbHZlcklwLTEuMC4wLjEiOiJZZXMiLCJyZXNvbHZlcklwLTI2MDY6NDcwMDo0NzAwOjoxMTExIjoiTm8iLCJyZXNvbHZlcklwLTI2MDY6NDcwMDo0NzAwOjoxMDAxIjoiTm8iLCJkYXRhY2VudGVyTG9jYXRpb24iOiJQUkciLCJpc1dhcnAiOiJObyIsImlzcE5hbWUiOiJDbG91ZGZsYXJlIiwiaXNwQXNuIjoiMTMzMzUifQ==

1.1.1.1 help link (during outage): [Will provide as soon as I get an outage.]

My ISP is Slovak Telekom.

This led me to use 8.8.8.8 as secondary DNS (and 1.1.1.1 as primary) but I would like to use only Cloudflare’s DNS.

I think this problem is not on Cloudflare’s end, as using OpenDNS results in the same type of outages, so I will contact my ISP in the future as well, but I do not know what I should be saying to them, what is my problem exactly?

Any help would be valued.

During outage, 1.1.1.1/help looks like the following:

The page never fully finishes loading, it is just stuck checking AN name & number.