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 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