DNS Negative Caching Checklist for School Recognition Display Content Changes
When a school changes the hostname that delivers recognition display content — migrating to a new content platform, correcting a subdomain, restructuring a district DNS zone, or switching from one cloud endpoint to another — every DNS resolver on the path between the kiosk and the internet may have already cached a negative answer for that hostname. A negative DNS answer, called an NXDOMAIN response (Name Non-Existent), tells the querying resolver that the hostname does not exist. Under RFC 2308, resolvers cache that negative response for a duration set by the zone’s SOA record. Until that negative cache entry expires — or is explicitly flushed — any kiosk, content player, or browser on the school network that queries the new hostname receives NXDOMAIN from cache rather than performing a fresh lookup against authoritative DNS.
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