<s>
In	O
public	B-Architecture
key	I-Architecture
infrastructure	I-Architecture
,	O
a	O
validation	B-Protocol
authority	I-Protocol
(	O
VA	O
)	O
is	O
an	O
entity	O
that	O
provides	O
a	O
service	O
used	O
to	O
verify	O
the	O
validity	O
or	O
revocation	O
status	O
of	O
a	O
digital	O
certificate	O
per	O
the	O
mechanisms	O
described	O
in	O
the	O
X.509	O
standard	O
and	O
(	O
page	O
69	O
)	O
.	O
</s>
<s>
The	O
dominant	O
method	O
used	O
for	O
this	O
purpose	O
is	O
to	O
host	O
a	O
certificate	B-Protocol
revocation	I-Protocol
list	I-Protocol
(	O
CRL	O
)	O
for	O
download	O
via	O
the	O
HTTP	B-Protocol
or	O
LDAP	B-Protocol
protocols	O
.	O
</s>
<s>
To	O
reduce	O
the	O
amount	O
of	O
network	O
traffic	O
required	O
for	O
certificate	O
validation	O
,	O
the	O
OCSP	B-Protocol
protocol	O
may	O
be	O
used	O
instead	O
.	O
</s>
<s>
While	O
a	O
validation	B-Protocol
authority	I-Protocol
is	O
capable	O
of	O
responding	O
to	O
a	O
network-based	O
request	O
for	O
a	O
CRL	O
,	O
it	O
lacks	O
the	O
ability	O
to	O
issue	O
or	O
revoke	O
certificates	O
.	O
</s>
<s>
It	O
must	O
be	O
continuously	O
updated	O
with	O
current	O
CRL	O
information	O
from	O
a	O
certificate	B-Architecture
authority	I-Architecture
which	O
issued	O
the	O
certificates	O
contained	O
within	O
the	O
CRL	O
.	O
</s>
<s>
While	O
this	O
is	O
a	O
potentially	O
labor-intensive	O
process	O
,	O
the	O
use	O
of	O
a	O
dedicated	O
validation	B-Protocol
authority	I-Protocol
allows	O
for	O
dynamic	O
validation	O
of	O
certificates	O
issued	O
by	O
an	O
offline	B-Protocol
root	I-Protocol
certificate	I-Protocol
authority	I-Protocol
.	O
</s>
<s>
While	O
the	O
root	O
CA	O
itself	O
will	O
be	O
unavailable	O
to	O
network	O
traffic	O
,	O
certificates	O
issued	O
by	O
it	O
can	O
always	O
be	O
verified	O
via	O
the	O
validation	B-Protocol
authority	I-Protocol
and	O
the	O
protocols	O
mentioned	O
above	O
.	O
</s>
<s>
The	O
ongoing	O
administrative	O
overhead	O
of	O
maintaining	O
the	O
CRLs	O
hosted	O
by	O
the	O
validation	B-Protocol
authority	I-Protocol
is	O
typically	O
minimal	O
,	O
as	O
it	O
is	O
uncommon	O
for	O
root	O
CAs	O
to	O
issue	O
(	O
or	O
revoke	O
)	O
large	O
numbers	O
of	O
certificates	O
.	O
</s>
