notice when you're confused
read the specification
do experiments
spy on it
what's DNS?
implement your own terrible version
Slide 9
Slide 9 text
No content
Slide 10
Slide 10 text
No content
Slide 11
Slide 11 text
No content
Slide 12
Slide 12 text
No content
Slide 13
Slide 13 text
No content
Slide 14
Slide 14 text
notice when you're confused
read the specification
do experiments
spy on it
what's DNS?
implement your own terrible version
Slide 15
Slide 15 text
No content
Slide 16
Slide 16 text
No content
Slide 17
Slide 17 text
$ dig example.com
example.com. 86400 IN A 93.184.216.34
Slide 18
Slide 18 text
$ dig example.com
example.com. 86400 IN A 93.184.216.34
Slide 19
Slide 19 text
+noall +answer
.digrc
Slide 20
Slide 20 text
No content
Slide 21
Slide 21 text
No content
Slide 22
Slide 22 text
No content
Slide 23
Slide 23 text
No content
Slide 24
Slide 24 text
No content
Slide 25
Slide 25 text
browser resolver authoritative
nameservers
DNS query
DNS query
where's example.com?
where's example.com?
93.184.216.34! 93.184.216.34!
Slide 26
Slide 26 text
resolver
browser
what's the IP for
example.com?
hmm, I'll look in
my cache...
Slide 27
Slide 27 text
No content
Slide 28
Slide 28 text
No content
Slide 29
Slide 29 text
No content
Slide 30
Slide 30 text
No content
Slide 31
Slide 31 text
No content
Slide 32
Slide 32 text
No content
Slide 33
Slide 33 text
No content
Slide 34
Slide 34 text
browser resolver authoritative
nameservers
DNS query
DNS query
where's new.jvns.ca?
where's new.jvns.ca?
NXDOMAIN NXDOMAIN
Slide 35
Slide 35 text
No content
Slide 36
Slide 36 text
No content
Slide 37
Slide 37 text
No content
Slide 38
Slide 38 text
“The TTL of this record is set
from the minimum of the MINIMUM
field of the SOA record and the
TTL of the SOA itself, and
indicates how long a resolver may
cache the negative answer.”