On Tue, Oct 5, 2021 at 1:47 PM Miles Fidelman <mfidel...@meetinghouse.net> wrote:
> jcur...@istaff.org wrote: > > Fairly abstract - Facebook Engineering - > https://m.facebook.com/nt/screen/?params=%7B%22note_id%22%3A10158791436142200%7D&path=%2Fnotes%2Fnote%2F&_rdr > <https://m.facebook.com/nt/screen/?params=%7B%22note_id%22:10158791436142200%7D&path=/notes/note/&_rdr> > > Also, Cloudflare’s take on the outage - > https://blog.cloudflare.com/october-2021-facebook-outage/ > > FYI, > /John > > This may be a dumb question, but does this suggest that Facebook publishes > rather short TTLs for their DNS records? Otherwise, why would an internal > failure make them unreachable so quickly? > Looks like 60 seconds: $ dig +norec star-mini.c10r.facebook.com. @d.ns.c10r.facebook.com. ; <<>> DiG 9.10.6 <<>> +norec star-mini.c10r.facebook.com. @ d.ns.c10r.facebook.com. ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25582 ;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;star-mini.c10r.facebook.com. IN A ;; ANSWER SECTION: star-mini.c10r.facebook.com. 60 IN A 157.240.229.35 ;; Query time: 42 msec ;; SERVER: 185.89.219.11#53(185.89.219.11) ;; WHEN: Tue Oct 05 14:01:06 EDT 2021 ;; MSG SIZE rcvd: 72 ... and cue the "Bwahahhaha! If *I* ran Facebook I'd make the TTL be [2 sec|30sec|5min|1h|6h+3sec|1day|6months|maxint32]" threads.... Choosing the TTL is a balancing act between stability, agility, load, politeness, renewal latency, etc -- but I'm sure NANOG can boil it down to "They did it wrong!..." W > Miles Fidelman > > -- > In theory, there is no difference between theory and practice. > In practice, there is. .... Yogi Berra > > Theory is when you know everything but nothing works. > Practice is when everything works but no one knows why. > In our lab, theory and practice are combined: > nothing works and no one knows why. ... unknown > > -- The computing scientist’s main challenge is not to get confused by the complexities of his own making. -- E. W. Dijkstra
