Dynamic IPs in Pool

Server operators
1

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?

2

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.

1 Like
3

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

For example, whatismyipaddress.com is calling the concerned IP address “Likely Static IP”.

asass
asass818Ă—742 144 KB

4

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

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.