<s>
PKI	B-Protocol
Resource	I-Protocol
Query	I-Protocol
Protocol	I-Protocol
(	O
PRQP	O
)	O
is	O
an	O
Internet	B-Protocol
protocol	I-Protocol
used	O
for	O
obtaining	O
information	O
about	O
services	O
associated	O
with	O
an	O
X.509	O
Certificate	B-Architecture
Authority	I-Architecture
.	O
</s>
<s>
Messages	O
communicated	O
via	O
PRQP	O
are	O
encoded	O
in	O
ASN.1	B-Protocol
and	O
are	O
usually	O
communicated	O
over	O
HTTP	B-Protocol
.	I-Protocol
</s>
<s>
DNS	B-Protocol
,	O
local	O
database	O
,	O
etc	O
.	O
</s>
<s>
latter	O
carries	O
information	O
(	O
inside	O
CA	B-Architecture
certificates	I-Architecture
)	O
about	O
offered	O
services	O
.	O
</s>
<s>
HTTP	B-Protocol
,	O
FTP	B-Protocol
,	O
LDAP	B-Protocol
or	O
SMTP	B-Protocol
)	O
.	O
</s>
<s>
periodic	O
reissuing	O
,	O
but	O
it	O
would	O
be	O
feasible	O
for	O
the	O
CA	B-Architecture
certificate	I-Architecture
itself	O
.	O
</s>
<s>
to	O
servers	O
directly	O
in	O
the	O
DNS	B-Protocol
(	O
RFC	O
1035	O
)	O
.	O
</s>
<s>
The	O
basic	O
idea	O
is	O
to	O
have	O
the	O
client	O
query	O
the	O
DNS	B-Protocol
for	O
a	O
specific	O
SRV	B-Protocol
record	I-Protocol
.	O
</s>
<s>
(	O
the	O
_tcp	O
means	O
the	O
client	O
requesting	O
a	O
TCP	B-Protocol
enabled	O
LDAP	B-Protocol
server	O
)	O
.	O
</s>
<s>
The	O
DC	O
attributes	O
are	O
used	O
to	O
specify	O
domain	O
components	O
of	O
a	O
DNS	B-Protocol
name	I-Protocol
,	O
</s>
<s>
to	O
DNS	B-Protocol
records	O
because	O
the	O
DC	O
format	O
is	O
not	O
widely	O
adopted	O
by	O
existing	O
CAs	O
.	O
</s>
