Live Interop

Live interoperability results

The Live interop workflow runs every Monday (and on demand) on GitHub-hosted runners and queries public servers with every ntpstats client. The latest results are in the workflow's job summary, and the first run of each month is recorded in the open dataset in data/interop/ (JSON lines, schema in its README). The dataset ships with every release and is therefore archived on Zenodo with it:

ntpstats dataset data/interop                 # availability, offsets, protocol support per server
ntpstats info data/interop --all-peers        # one series per test and server

Below is the first run, kept as a reference.

2026-09-29 11:26 UTC (ntpstats 2.2.0, GitHub Actions ubuntu-latest, IPv4)

NTPv4 (SNTP, random transmit timestamp)

server	address	stratum	refid	offset	delay	root dist.
time.cloudflare.com	162.159.200.123	3	10.157.8.4	-65.6 µs	5.15 ms	6.1 ms
time.google.com	216.239.35.0	1	GOOG	-30.5 µs	6.08 ms	91.6 µs
ptbtime1.ptb.de	192.53.103.108	1	PTB	-121 µs	93.7 ms	68.7 µs
time.nist.gov	132.163.97.4	1	NIST	-1.85 ms	47.1 ms	610 µs
pool.ntp.org	23.172.120.58	2	54.219.187.236	-700 µs	108 ms	526 µs
ntp.ubuntu.com	185.125.190.58	2	29.88.99.4	-695 µs	79 ms	3.51 ms

NTS (RFC 8915): two authenticated exchanges per server

server	NTP host:port	stratum	offset	delay	cookies left
time.cloudflare.com	time.cloudflare.com:123	3	-71.2 µs	5.2 ms	8
nts.netnod.se	194.58.205.197:4123	1	-1.69 ms	108 ms	8
ptbtime1.ptb.de	ptbtime1.ptb.de:123	1	474 µs	95.9 ms	8
ntppool1.time.nl	ntppool1.time.nl:123	1	44 µs	91.8 ms	8
ntp.3eck.net	ntp.3eck.net:123	2	-525 µs	95.6 ms	8

Notes:

• Netnod hands out a different NTP server and port (4123) through the NTS-KE server and port negotiation records, which the client follows.
• "cookies left = 8" after two queries shows that cookie renewal works: each authenticated response returned a fresh cookie encrypted with the S2C key.
• The large offsets and delays of distant servers (PTB, Netnod and NIST seen from a US data centre) come from path asymmetry, not clock error. This is exactly what the offset/delay wedge and the delay-weighted estimators in ntpstats are for.

NTPv5 (draft-ietf-ntp-ntpv5-09 upgrade probe)

None of the probed public servers (Cloudflare, PTB, time.nl) offered NTPv5 at the time of the run. The v5 client is verified against a local draft-09 test server (see tests/test_sntp.py) whose wire format was cross-checked with ntpd-rs.