<s>
DNS	B-Protocol
management	I-Protocol
software	I-Protocol
is	O
computer	B-Application
software	I-Application
that	O
controls	O
Domain	B-Protocol
Name	I-Protocol
System	I-Protocol
(	O
DNS	B-Protocol
)	O
server	O
clusters	O
.	O
</s>
<s>
DNS	B-Protocol
data	O
is	O
typically	O
deployed	O
on	O
multiple	O
physical	O
servers	O
.	O
</s>
<s>
The	O
main	O
purposes	O
of	O
DNS	B-Protocol
management	I-Protocol
software	I-Protocol
are	O
:	O
</s>
<s>
The	O
way	O
to	O
register	O
them	O
was	O
by	O
email	O
and	O
the	O
way	O
to	O
publish	O
them	O
was	O
BIND	B-Protocol
.	O
</s>
<s>
As	O
the	O
number	O
of	O
domains	O
and	O
,	O
so	O
too	O
did	O
the	O
quantity	O
of	O
DNS	B-Protocol
data	O
and	O
the	O
time	O
required	O
to	O
manage	O
it	O
.	O
</s>
<s>
Sysadmins	O
responded	O
by	O
writing	O
Perl	B-Language
or	O
Shell	B-Operating_System
scripts	O
that	O
helped	O
automate	O
DNS	B-Protocol
changes	O
.	O
</s>
<s>
The	O
closest	O
thing	O
to	O
widely	O
available	O
DNS	B-Protocol
management	I-Protocol
software	I-Protocol
was	O
the	O
BIND	B-Protocol
module	O
in	O
webmin	B-Application
,	O
which	O
provided	O
web	O
tools	O
for	O
editing	O
BIND	B-Protocol
zone	O
files	O
.	O
</s>
<s>
During	O
the	O
late	O
1990s	O
,	O
the	O
sheer	O
quantity	O
of	O
DNS	B-Protocol
data	O
was	O
overwhelming	O
the	O
tools	O
available	O
to	O
manage	O
it	O
.	O
</s>
<s>
The	O
cost	O
of	O
managing	O
the	O
data	O
instigated	O
the	O
birth	O
of	O
DNS	B-Protocol
management	I-Protocol
software	I-Protocol
.	O
</s>
<s>
In	O
1998	O
,	O
three	O
of	O
the	O
largest	O
web	O
hosting	O
companies	O
(	O
HostPro	O
,	O
Interland	O
,	O
and	O
Vservers	O
)	O
each	O
hosted	O
about	O
100,000	O
DNS	B-Protocol
zones	O
.	O
</s>
<s>
DNS	B-Protocol
changes	O
were	O
made	O
by	O
telnetting	O
to	O
a	O
BIND	B-Protocol
master	O
and	O
editing	O
zone	O
files	O
with	O
a	O
text	O
editor	O
.	O
</s>
<s>
A	O
staff	O
of	O
several	O
DNS	B-Protocol
admins	O
performed	O
this	O
task	O
all	O
day	O
,	O
every	O
day	O
.	O
</s>
<s>
Their	O
changes	O
would	O
only	O
take	O
effect	O
after	O
a	O
BIND	B-Protocol
reload	O
.	O
</s>
<s>
Because	O
disks	O
were	O
slow	O
,	O
it	O
took	O
several	O
hours	O
for	O
BIND	B-Protocol
to	O
do	O
a	O
full	O
reload	O
.	O
</s>
<s>
If	O
a	O
DNS	B-Protocol
admin	O
made	O
a	O
typo	O
in	O
a	O
zone	O
file	O
,	O
BIND	B-Protocol
would	O
fail	O
to	O
parse	O
that	O
file	O
and	O
die	O
.	O
</s>
<s>
Whoever	O
noticed	O
BIND	B-Protocol
was	O
n't	O
running	O
would	O
have	O
to	O
read	O
the	O
logs	O
,	O
find	O
the	O
zone	O
file	O
with	O
the	O
error	O
,	O
manually	O
review	O
the	O
file	O
,	O
fix	O
the	O
error	O
,	O
and	O
then	O
try	O
starting	O
BIND	B-Protocol
back	O
up	O
.	O
</s>
<s>
Once	O
up	O
,	O
the	O
changes	O
could	O
propagate	O
to	O
the	O
DNS	B-Protocol
slaves	O
via	O
zone	O
transfers	O
.	O
</s>
<s>
While	O
struggling	O
with	O
the	O
challenges	O
of	O
editing	O
zone	O
files	O
,	O
more	O
than	O
a	O
few	O
sysadmins	O
noticed	O
that	O
SQL	B-Language
is	O
a	O
terrific	O
place	O
to	O
store	O
DNS	B-Protocol
data	O
.	O
</s>
<s>
By	O
moving	O
the	O
Single	B-Application
Source	I-Application
of	I-Application
Truth	I-Application
from	O
text	O
files	O
into	O
SQL	B-Language
,	O
DNS	B-Protocol
data	O
could	O
be	O
validated	O
and	O
constrained	O
before	O
acceptance	O
into	O
the	O
database	O
.	O
</s>
<s>
Export	O
scripts	O
could	O
convert	O
the	O
SQL	B-Language
to	O
zone	O
files	O
.	O
</s>
<s>
Among	O
large	O
hosting	O
providers	O
,	O
it	O
became	O
fashionable	O
to	O
store	O
DNS	B-Protocol
data	O
in	O
SQL	B-Language
and	O
build	O
a	O
custom	O
interface	O
for	O
managing	O
it	O
.	O
</s>
<s>
mysqlBind	B-Protocol
is	O
one	O
such	O
DNS	B-Protocol
manager	O
.	O
</s>
<s>
It	O
provides	O
a	O
web	O
interface	O
for	O
data	O
input	O
and	O
exports	O
the	O
data	O
to	O
BIND	B-Protocol
zone	O
files	O
.	O
</s>
<s>
In	O
2000	O
,	O
Daniel	O
J	O
Bernstein	O
released	O
Djbdns	B-Protocol
.	O
</s>
<s>
One	O
of	O
the	O
novel	O
features	O
was	O
that	O
tinydns	B-Protocol
,	O
the	O
included	O
authoritative	O
DNS	B-Protocol
server	O
,	O
served	O
DNS	B-Protocol
directly	O
from	O
a	O
CDB	B-General_Concept
database	I-General_Concept
.	O
</s>
<s>
The	O
cdb	B-General_Concept
had	O
to	O
be	O
compiled	O
from	O
a	O
plain	O
text	O
file	O
whose	O
format	O
was	O
designed	O
to	O
be	O
edited	O
by	O
scripts	O
.	O
</s>
<s>
and	O
a	O
number	O
of	O
DNS	B-Protocol
managers	O
were	O
released	O
for	O
it	O
,	O
including	O
:	O
,	O
,	O
and	O
.	O
</s>
<s>
In	O
2005	O
,	O
PowerDNS	B-Language
was	O
released	O
.	O
</s>
<s>
One	O
of	O
its	O
features	O
was	O
the	O
ability	O
to	O
serve	O
DNS	B-Protocol
data	O
directly	O
out	O
of	O
the	O
SQL	B-Language
database	I-Language
,	O
bypassing	O
the	O
export	O
step	O
entirely	O
.	O
</s>
<s>
PowerDNS	B-Language
also	O
spawned	O
a	O
number	O
of	O
DNS	B-Protocol
managers	O
that	O
provide	O
web	O
interfaces	O
to	O
its	O
SQL	B-Language
data	O
store	O
.	O
</s>
<s>
Using	O
the	O
RFC2136	O
DDNS	B-Application
update	O
protocol	O
,	O
it	O
is	O
possible	O
to	O
change	O
DNS	B-Protocol
zones	O
without	O
accessing	O
the	O
zone	O
files	O
.	O
</s>
<s>
DNS	B-Protocol
service	O
providers	O
often	O
deploy	O
different	O
types	O
of	O
DNS	B-Protocol
servers	O
in	O
their	O
networks	O
.	O
</s>
<s>
In	O
addition	O
,	O
different	O
answers	O
may	O
be	O
provided	O
to	O
DNS	B-Protocol
clients	O
based	O
on	O
the	O
clients	O
 '	O
geographic	O
location	O
,	O
as	O
determined	O
by	O
their	O
IP	O
address	O
(	O
GeoIP	B-Application
)	O
.	O
</s>
<s>
The	O
most	O
practical	O
way	O
to	O
manage	O
such	O
critical	B-Architecture
Internet	I-Architecture
infrastructure	I-Architecture
has	O
been	O
to	O
rely	O
on	O
databases	O
and	O
complex	O
DNS	B-Protocol
management	I-Protocol
software	I-Protocol
to	O
ensure	O
homogeneity	O
and	O
avoid	O
single	O
points	O
of	O
deployment	O
errors	O
.	O
</s>
<s>
Name	O
NicTool	O
Infoblox	O
VegaDNS	O
mysqlBind	B-Protocol
Webmin	B-Application
Admin4	O
MicrosoftDNS	O
Manager	O
fmDNSMicetro	O
BIND	B-Protocol
tinydns	B-Protocol
PowerDNS	B-Language
?	O
</s>
<s>
NSD	B-Protocol
?	O
</s>
<s>
The	O
BIND	B-Protocol
zone	O
file	O
format	O
is	O
a	O
widely	O
used	O
industry	O
standard	O
documented	O
in	O
RFC	O
1035	O
.	O
</s>
<s>
Several	O
other	O
DNS	B-Protocol
servers	O
,	O
including	O
PowerDNS	B-Language
,	O
NSD	B-Protocol
,	O
Knot	B-Protocol
DNS	I-Protocol
,	O
Microsoft	B-Protocol
DNS	I-Protocol
Server	O
,	O
and	O
Micetro	O
by	O
MEn&Mice	O
have	O
the	O
ability	O
to	O
read	O
BIND	B-Protocol
zone	O
files	O
and	O
serve	O
from	O
them	O
.	O
</s>
<s>
Name	O
NicTool	O
VegaDNS	O
mysqlBind	B-Protocol
Webmin	B-Application
Admin4	O
Microsoft	B-Protocol
DNS	I-Protocol
Manager	O
ProBIND	O
fmDNSMicetro	O
A	O
,	O
NS	O
,	O
SOA	O
,	O
PTR	O
MX	O
,	O
TXT	O
,	O
CNAME	O
KEY	O
AAAA	O
LOC	O
SRV	O
NAPTR	O
SSHFP	O
RRSIG	O
NSEC	O
DNSKEY	O
DS	O
NSEC3	O
NSEC3PARAM	O
IPSECKEY	O
?	O
</s>
<s>
Microsoft	B-Protocol
DNS	I-Protocol
manager	O
supports	O
DNSSEC	O
from	O
Windows	O
Server	O
2012	O
onwards	O
.	O
</s>
<s>
Primary	O
reasons	O
for	O
DNS	B-Protocol
providers	O
(	O
especially	O
root	O
operators	O
)	O
to	O
use	O
different	O
DNS	B-Protocol
servers	O
is	O
code	O
diversity	O
and	O
application	O
performance	O
.	O
</s>
<s>
Code	O
diversity	O
makes	O
it	O
less	O
likely	O
that	O
a	O
performance	O
or	O
security	O
bug	O
in	O
one	O
DNS	B-Protocol
server	O
could	O
be	O
exploited	O
to	O
inflict	O
a	O
Denial	O
of	O
Service	O
attack	O
upon	O
an	O
organization	O
.	O
</s>
<s>
It	O
is	O
for	O
this	O
reason	O
that	O
NSD	B-Protocol
and	O
Knot	B-Protocol
DNS	I-Protocol
are	O
frequently	O
used	O
by	O
root	O
and	O
TLD	O
operators	O
.	O
</s>
<s>
DNS	B-Protocol
management	I-Protocol
software	I-Protocol
can	O
greatly	O
simplify	O
publishing	O
DNS	B-Protocol
data	O
to	O
varying	O
DNS	B-Protocol
servers	O
.	O
</s>
