# Dynamic IPs in Pool

**URL:** <https://community.ntppool.org/t/dynamic-ips-in-pool/2323>\
**Category:** Server operators\
**Created:** [March 24, 2022, 5:25pm UTC](https://community.ntppool.org/t/dynamic-ips-in-pool/2323 "2022-03-24T17:25:20Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Skavoovie](https://avatars.discourse-cdn.com/v4/letter/s/5f9b8f/32.png) [@Skavoovie](https://community.ntppool.org/u/Skavoovie)\
**Post date:** [March 24, 2022, 5:25pm UTC](https://community.ntppool.org/t/dynamic-ips-in-pool/2323/1 "2022-03-24T17:25:20Z")

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Happened to take a look at the source stats on one my client machines that is using the NTP pool, and was surprised to find the PTR record of one of the pool members I was polling indicated it was a DHCP pool residential Internet service IP (specifically a Verizon Fios DHCP residential IP address).

`pool-173-72-24-4.cmdnnj.fios.verizon.net`

Joining the pool using a dynamic IP address seems to me to be a bad idea as the IP could change at any given time. Some ISPs do not regularly force their customers to a new IP lease (for example, Verizon Fios is commonly known to not regularly force IP lease changes), but a simple power outage or connection issue would lead generally lead to a new IP lease.

Is my thinking wrong? Is this something that has been discussed / decided previously and was decided to be okay?

If not, would it make sense to perform a PTR DNS lookup when someone attempts to add a host to the NTP Pool, and if the PTR contains certain keywords (i.e. pool, dhcp, dyn, dynamic, etc.), not allow the IP to join the pool?

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**Author:** ![Bas](https://sea2.discourse-cdn.com/flex016/user_avatar/community.ntppool.org/bas/32/465_2.png) [@Bas](https://community.ntppool.org/u/Bas)\
**Post date:** [March 25, 2022, 1:37pm UTC](https://community.ntppool.org/t/dynamic-ips-in-pool/2323/2 "2022-03-25T13:37:00Z")

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If your IP changes the monitor will lower your score and drops it automatically out of the pool-dns.

Some dynamic-IP’s do not change at all until a power-cut or long disconnect.

You will make it impossible for such users to join the pool.

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**Author:** ![HAHAHAHA](https://sea2.discourse-cdn.com/flex016/user_avatar/community.ntppool.org/hahahaha/32/2475_2.png) [@HAHAHAHA](https://community.ntppool.org/u/HAHAHAHA)\
**Post date:** [March 26, 2022, 2:51am UTC](https://community.ntppool.org/t/dynamic-ips-in-pool/2323/3 "2022-03-26T02:51:26Z")

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It’s hard to tell for sure if a particular IP address is being used as dynamic or fixed allocation.

For example, [whatismyipaddress.com](http://whatismyipaddress.com) is calling the concerned IP address “Likely Static IP”.

 ![asass](https://us1.discourse-cdn.com/flex016/uploads/ntppool/original/1X/3963f6b9228d4baa437ac8220c41970ee8016729.png)

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<div class="post-metadata">

**Author:** ![Bas](https://sea2.discourse-cdn.com/flex016/user_avatar/community.ntppool.org/bas/32/465_2.png) [@Bas](https://community.ntppool.org/u/Bas)\
**Post date:** [March 27, 2022, 7:37pm UTC](https://community.ntppool.org/t/dynamic-ips-in-pool/2323/4 "2022-03-27T19:37:12Z")

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Mine is static, it should be able to tell because of my PTR-record.  
Doesn’t seem to read those records 😄

Simple check should be:

bas@workstation:~$ nslookup heppen.be  
Server: 127.0.0.53  
Address: 127.0.0.53#53

Non-authoritative answer:  
Name: heppen.be  
Address: 77.109.90.72

bas@workstation:~$ nslookup 77.109.90.72  
72.90.109.77.in-addr.arpa name = heppen.be.

Authoritative answers can be found from:

bas@workstation:~$

That is a clear indication that it is static.

However, not all ISP’s are willing to give you a personal PTR.