Subj : Re: syncterm bbs port discovery
To   : poindexter FORTRAN
From : Tracker1
Date : Sat Jul 16 2022 13:42:57

On 7/9/22 09:02, poindexter FORTRAN wrote:
 >> Keep in mind an SRV record hostname must point to a servers A or
 >> AAAA address and not a CNAME. Otherwise, seems reasonable.
 >
 > My experience setting up DNS is long in the past, Bind 4.9 in 1993?
 >
 > I don't recall if there was any downside to setting multiple A records
 > pointing to one IP, versus one A record with multiple CNAME records
 > pointing to it?
 >
 > No downside, aside from having to change multiple DNS entries when the
 > originating IP changes?

You can pretty safely have longer lifetimes for CNAME than you'd want to 
use for A records.  I generally set CNAME for at least a week, and A 
records for 15m to a day.

Depending on the DNS server, the round-trip for two requests could 
impact things. If you care about the time to render a website, it can 
matter a lot.  Don't know if it's changed, but GoDaddy's DNS servers had 
particularly bad latency for most people, and handled a high portion of 
the internet.  Which is a large part of why google created their 
distributed DNS that sometimes exceeds the specified timing in favor of 
cached results.  Going under 15m for A record likely will be ignored by 
Google's DNS cache.

It's not too hard to do your own caching DNS lookups. I use pihole 
locally and fall back to the Cloudflare DNS servers, I have less trust 
of Google over time even though a lot of my domains have DNS at Google, 
I like their registrar interface, but considering moving them all.
-- 
Michael J. Ryan - tracker1@roughneckbbs.com
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