Look at it this way, anywhere that has resolvers forwarding to other resolvers that forward to yet another set of resolvers before the query gets to the root servers (anywhere with a complex network and multiple layers of firewalling) will have a succession of caches that need to clear .. so might take somewhat longer than whatever TTL you set. The recommendation therefore is to lower the TTL for a few days BEFORE you change your DNS records.
--srs ________________________________ From: NANOG <nanog-bounces+ops.lists=gmail....@nanog.org> on behalf of Laura Smith via NANOG <nanog@nanog.org> Sent: Saturday, August 10, 2024 7:46:31 PM To: nanog@nanog.org <nanog@nanog.org> Subject: Any ideas how long gmail cache DNS records ? In typical "Google knows best" style they appear to be ignoring SOA and TTL and doing their own thing. Changed DNS severs and MX records, other public mail services have picked it up no problem. Gmail however appear to be insisting on continuing to deliver to the old mail servers for god knows how much longer ? Any ideas how long I can expect this to go on for before they Do The Right Thing (TM) ?
