Comment by teddyh
7 years ago
I operate authoritative name servers for almost 10.000 domains. Originally, I used a default TTL of 2 days, as recommended by RIPE-203¹ (which is also compatible with the recommendations of RFC 1912²), but this was not accepted by users, who didn’t want to wait two days. Therefore, for all records except SOA and NS records, I changed the default TTL to one hour, which I still use as the default value unless a change is scheduled and/or planned, in which case I lower it to 5 minutes. I do not want to lower it any more, as I’ve heard rumors of buggy resolvers interpreting “too low” TTLs as bad, and reverting to some very-high default TTL, and thereby wrecking my carefully planned DNS changeover. I have, however, not seen any real numbers or good references on what numbers are “too low”, and would like to hear from anyone who might have some information on this.
Unless you have insight into the end users DNS deployments I would say this is the appropriate amount of caution to apply. Besides just TTL being low, a frequent issue I had when first migrating to AWS years ago was CNAME to CNAME records not resolving among some end users. Primary schools were the worst offenders, I assume some of them still have Novell deployed.
Would you mind sharing the service?
The service? What service? What do you mean?
You said you run authoritative servers- I assume you provide DNS hosting. I'm curious which provider you run.
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