Net Speed set to 512 Kbit/s: still in global zone, but almost no traffic

Server operators
1

Hi everyone,

I’m running an NTP server in Italy (185.14.78.115) and recently reduced its Net Speed setting to the minimum value of 512 Kbit/s.
From what I’ve read in previous discussions, setting the Net Speed to 512 Kbit/s should automatically remove the server from the global zone (@), keeping it available only in regional zones.

However, my server’s page still shows three zones:@ (Global) europe it (Italy) .

My intention is to keep the server available only in the Italian pool, rather than making it available globally.
Is this the expected behavior? Does the Net Speed setting affect only the global zone, or should the continental zone also be removed?

I’ve also noticed something interesting: with the Net Speed set to 512 Kbit/s, the number of incoming NTP requests is extremely low, around 30–40 requests per second.

This is practically the same amount of traffic I receive when the server is set to monitoring only.

This doesn’t seem entirely normal to me, especially considering that there are relatively few IPv4 servers available in the Italian pool (only 39 servers)

I would therefore expect my server to receive at least some noticeable traffic from the Italian pool, even with the minimum Net Speed setting.

Out of curiosity, I also ran a small (long…) test querying nine authoritative DNS servers for it.pool.ntp.org, performing 200 queries per server. The queries were deliberately rate-limited, with a 1000 ms delay between consecutive requests, to avoid generating excessive DNS traffic.

Out of 1800 valid authoritative responses, my IP address did not appear even once.

I realize this isn’t necessarily a statistically representative test, since DNS responses may be influenced by geographic selection and other factors, but the result caught my attention.

This makes me wonder whether setting the Net Speed to 512 Kbit/s effectively prevents the server from being included in DNS responses, despite it still being listed in the it zone.

So, I have a few questions:

  1. Is it normal for a server configured at 512 Kbit/s to remain listed in the global (@) and continental (europe) zones?

  2. Does the minimum Net Speed setting significantly reduce DNS selection probability, even in a country with relatively few available servers?

  3. Is receiving only 30–40 NTP requests per second at this setting expected, or could it indicate that the server is effectively not being selected?

  4. Is there a way to restrict participation exclusively to the Italian zone?

Thanks in advance!

image
image288×221 10.3 KB

2

The “client distribution” metrics at the bottom of the page - pool.ntp.org: Statistics for 185.14.78.115 (I’m including it because you already told above which server is yours) says how many 10000’s of the requests the IP is in for queries from Italy. It looks like about 1/2000?

As you pointed out there aren’t that many servers in Italy, so the 1/2000 is actually 39x MORE than what “512kb” should work out to, but the system needs more servers to that accurately in some cases.

On average the system gets 2600 queries a second from Italy, so about once a second someone is getting your IP (~100k times a day!)

The hourly peak (for a few seconds) is 5-10x more than the average.

3

Thanks for the detailed explanation! That makes much more sense now.

Just one more question: is it normal that my server still shows all three zones (@, europe, and it) with Net Speed set to 512 Kbit/s?

4

Hi

I am not running the pool but just a server operator who does some monitoring so others may have a different point of view.

I am reading that to be that you only want requests from ip addresses in Italy. My answer would be no it is not possible - that I know of.

The problem is that when the pool receives a DNS request for pool.ntp.org it needs to work out where the request is coming from so it can reply with what it thinks is a nearby NTP server ip addresses. The pool uses GeoDNS to work that out but the problem is GeoDNS is not that reliable in picking the source location based on the ip address. For example if a user in France makes a request and the pool thinks the source ip address is in Italy then it could send the request from France to your Itialian server. Think of it this way - A user in France makes a DNS request to Cloudflare. The France Cloudflare site is under mantenance so the anycast request ends up going to Cloudflare Italy which looks in its cache and/or asks the pool. The pool “thinks” the request is from Italy so replies with your server IP address in Italy.

Take https://community.ntppool.org/t/problems-with-cloudflare-dns-in-nz/3512 for example. A while back asking Cloudflare for an NTP server from New Zealand would return addresses from Argentina.

Another example is that every few hours I ask the pool DNS servers where they think a request is coming from. A sample of the results from yesterday for an Alibaba server in Manila -

======== Pool Geodns guess for for ph-mnl-alibaba...
      6  8.8.8.8 ph asia @
      4  9.9.9.9 us north-america @
      2  9.9.9.9 ph asia @
      5  1.1.1.1 ph asia @
      1  1.1.1.1 hk asia @

All six of the requests to Google DNS said the source ip was in Manila. Asking Quad9 and 4 of the 6 requests said the request was from the US with 2 in Manila. For Cloudflare 5 in Manila and one in Hong Kong.

Based on that I do not think it would be possible to restrict your server to only receive requests from inside Italy if that was the question you were asking :grinning_face: