# Doubt about server rotation in Pool DNS **URL:** \ **Category:** Uncategorized\ **Created:** [August 22, 2021, 12:27am UTC](https://community.ntppool.org/t/doubt-about-server-rotation-in-pool-dns/2138 "2021-08-22T00:27:51Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Clock](https://sea2.discourse-cdn.com/flex016/user_avatar/community.ntppool.org/clock/32/757_2.png) [@Clock](https://community.ntppool.org/u/Clock)\ **Post date:** [August 22, 2021, 12:27am UTC](https://community.ntppool.org/t/doubt-about-server-rotation-in-pool-dns/2138/1 "2021-08-22T00:27:51Z")
Recently I’ve been checking the DNS records of the [us.pool.ntp.org](http://us.pool.ntp.org) address and realized that one of my servers (with netspeed at full speed) constantly appears as record A on various DNS servers in North America. However, I have a secondary server also located in the USA, but with netspeed at 25Mb/s. This server receives about 300 requests per second, and even after performing multiple checks on the [us.pool.ntp.org](http://us.pool.ntp.org) and [noth-america.pool.ntp.org](http://noth-america.pool.ntp.org) domain, DNS servers have never returned the IP from that particular server. This leads me to believe, that depending on the netspeed set, the server IP is not included in the regional pool rotation list. If NTP traffic is not coming from the us and north america pool, in which pool domain is this server being distributed? ---
**Author:** ![marco.davids](https://sea2.discourse-cdn.com/flex016/user_avatar/community.ntppool.org/marco.davids/32/767_2.png) [@marco.davids](https://community.ntppool.org/u/marco.davids)\ **Post date:** [August 22, 2021, 9:33am UTC](https://community.ntppool.org/t/doubt-about-server-rotation-in-pool-dns/2138/2 "2021-08-22T09:33:10Z")
> [@Clock](#): > > Recently I’ve been checking the DNS records of the [us.pool.ntp.org](http://us.pool.ntp.org) address Just out of curiosity; how did you check? Hopefully not against your caching local resolver, but instead directly at (one of) the authoritatives of [pool.ntp.org](http://pool.ntp.org)? ---
**Author:** ![mlichvar](https://avatars.discourse-cdn.com/v4/letter/m/e79b87/32.png) [@mlichvar](https://community.ntppool.org/u/mlichvar)\ **Post date:** [August 22, 2021, 10:09am UTC](https://community.ntppool.org/t/doubt-about-server-rotation-in-pool-dns/2138/3 "2021-08-22T10:09:06Z")
The US zone has a large number of servers and many of them are configured at high speed. At the maximum 1Gb/s setting you would get only about 1% of the zone’s traffic. With the 25Mb/s speed you might need to make thousands of DNS requests to actually see your address. ---
**Author:** ![Clock](https://sea2.discourse-cdn.com/flex016/user_avatar/community.ntppool.org/clock/32/757_2.png) [@Clock](https://community.ntppool.org/u/Clock)\ **Post date:** [August 22, 2021, 6:45pm UTC](https://community.ntppool.org/t/doubt-about-server-rotation-in-pool-dns/2138/4 "2021-08-22T18:45:58Z")
I checked using the [https://dnschecker.org/](https://dnschecker.org/) service which queries several recursive DNS servers around the world. ---
**Author:** ![stevesommars](https://sea2.discourse-cdn.com/flex016/user_avatar/community.ntppool.org/stevesommars/32/2075_2.png) [@stevesommars](https://community.ntppool.org/u/stevesommars)\ **Post date:** [August 23, 2021, 9:47pm UTC](https://community.ntppool.org/t/doubt-about-server-rotation-in-pool-dns/2138/5 "2021-08-23T21:47:50Z")
I ran IPv4 DNS tests against one of the authoritative servers for [0123].us.pool.ntp.org 522 unique server addresses were returned, the number of servers in the zone is currently about 550. The distribution was highly skewed toward the high-rate servers, as it should be 2.67% 162.159.200.1 [time.cloudflare.com](http://time.cloudflare.com) 2.65% 162.159.200.123 [time.cloudflare.com](http://time.cloudflare.com) 0.008% My US-based pool server. Configured rate = 10Mbps. It is over 600 times more likely for a Cloudflare server to be selected than my server. ---
**Author:** ![Clock](https://sea2.discourse-cdn.com/flex016/user_avatar/community.ntppool.org/clock/32/757_2.png) [@Clock](https://community.ntppool.org/u/Clock)\ **Post date:** [August 24, 2021, 3:25am UTC](https://community.ntppool.org/t/doubt-about-server-rotation-in-pool-dns/2138/6 "2021-08-24T03:25:53Z")
The frequency of distribution of servers with low netspeed seems to be actually very small compared to servers with maximum netspeed. But judging by the amount of requests, it seems correct. We should also consider that many clients cache DNS results, ignoring new query to the pool zone.