In order for Pingdoms probe servers to make requests to a specific server, an IP address is needed. Most server are identified by a hostname, for example example.com, this address is unfortunately not routable on the Internet, an IP address needs to be looked up first.
This is done by making a DNS lookup to the name server example.com.
Our probes stored these lookups internally or used a central cache we had, this made for some really fast lookup times, but it could take a while before the probe servers detected changes to these DNS records.
We discussed and finally changed the way these lookups are made, each request our prbes make will include a regular DNS lookup without caching from now on. This will increase the response time somewhat for some checks, but that is reflecting more what a new request to your URL would look like. Changes to DNS records will be detected by the probes faster and issues with DNS lookups will be alerted on quicker as well.
We also provide a specific DNS check which make lookups for you URL to a specific name server to see if the correct IP address is returned.