So you've designed your redundant architecture and ensured that your data is being replicated across it? All set? Not quite. Within your DNS configuration there are two timers that we frequently see misconfigured - TTL values and the SOA expire value.
Frequently we see these left at default a default of one day (86400 seconds). Whilst these may suit many organisations it's worth taking a closer look to make sure that they match your expectation for your DNS services.
Having designed a redundant DNS infrastructure, one of the most common mistakes is failing to ensure that secondary nameservers can successfully replicate data for the domains it is hosting. The most common way this is done on the Internet is though zone transfers - the AXFR command. This command causes a DNS server to reply with all the data it knows for a domain.
