May 2009 Archives

"The pool is one hour off"

As mentioned a few months ago, NTP operates exclusively with UTC time. If your system is (typically) one hour off after syncing with the NTP Pool then it's because your operating system needs to be configured with the correct timezone and daylight saving time setting. If you live in a place that recently changed rules for daylight saving time you need to make sure you have the latest system updates installed.

Dynect DNS services

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The goal of the NTP Pool is to provide accurate time to everybody. Though internally it's really about serving DNS requests. Quite a lot of them, and ideally fast.

Through history we've ended up with using the 'pool.ntp.org' domain for client access which for performance isn't really optimal, but it's what we have. Through a bit of administrative division it ends up that just to find out who to ask for the IP of '1.fedora.pool.ntp.org' you have to send a whole lot of DNS requests out.

While the DNS system is resilient in handling failures, to get decent performance it's important that each "layer" has fast and highly available servers. To that end we're fortunate that Dynect are providing Anycast DNS services for the NTP Pool (about 300 million requests a month right now, and we're just getting started).

For now we're just using Dynect for the ntpns.org zone, but in the future we're looking forward to also using their failover system to help make sure the pool website is always available.