order, acl, deny, implicit Article Body: To pass the CCNA exam, you have to be able to write and troubleshoot access lists. As you climb the ladder toward the CCNP and CCIE, you'll see more and more uses for ACLs. Therefore, you had better know the basics! The use of "host" and "any" confuses some newcomers to ACLs, so let's take a look at that first. It is acceptable to configure a wildcard mask of all ones or all zeroes. A wildcard mask of 0.0.0.0 means the address specified in the ACL line must be matched exactly a wildcard mask of 255.255.255.255 means that all addresses will match the line. Wildcard masks have the option of using the word host to represent a wildcard mask of 0.0.0.0. Consider a configuration where only packets from IP source 10.1.1.1 should be allowed and all other packets denied. The following ACLs both do that. R3#conf t R3(config)#access-list 6 permit 10.1.1.1 0.0.0.0 R3(config)#conf t R3(config)#access-list 7 permit host 10.1.1.1 The keyword any can be used to represent a wildcard mask of 255.255.255.255. R3(config)#access-list 15 permit any Another often overlooked detail is the order of the lines in an ACL. Even in a two- or three-line ACL, the order of the lines in an ACL is vital. Consider a situation where packets sourced from 172.18.18.0 /24 will be denied, but all others will be permitted. The following ACL would do that. R3#conf t R3(config)#access-list 15 deny 172.18.18.0 0.0.0.255 R3(config)#access-list 15 permit any The previous example also illustrates the importance of configuring the ACL with the lines in the correct order to get the desired results. What would be the result if the lines were reversed? R3#conf t R3(config)#access-list 15 permit any R3(config)#access-list 15 deny 172.18.18.0 0.0.0.255 If the lines were reversed, traffic from 172.18.18.0 /24 would be matched against the first line of the ACL. The first line is ôpermit any", meaning all traffic is permitted. The traffic from 172.18.18.0/24 matches that line, the traffic is permitted, and the ACL stops running. The statement denying the traffic from 172.18.18.0 is never run. The key to writing and troubleshoot access lists is to take just an extra moment to read it over and make sure it's going to do what you intend it to do. It's better to realize your mistake on paper instead of once the ACL's been applied to an interface! Title: Cisco CCNA Certification Exam Tutorial: Configuring And Troubleshooting VTP Word Count: 426 Summary: The VLAN Trunking Protocol
piece
is
an
abstract
triptych
that
I
found
while
I
was
in
Atlanta
buying
religious
paintings
The
piece
was
called
Guardian
Angel
and
I
love
it
My
patrons
fell
in
love
with
it
as
well
They
have
asked
me
to
track
down
the
artist
and
see
if
he
has
anymore
religious
paintings
available
The
only
religious
paintings
that
I
actually
do
not
buy
are
ones
that
reflect
the
image
of
Jesus
on
the
cross
I
don’t
have
a
problem
with
them
some
of
them
are
extremely
well
done
and
would
more
than
likely
sell
well
but
my
investors
made
it
very
clear
when
they
financed
the
gallery
that
I
would
not
put
that
image
into
it
PPPPP
683
Ajello
Candles
The
motto
of
the
Ajello
Candle
Company
is
“It’s
better
to
light
a
candle
than
to
curse
the
darkness”
This
candle
making
company
has
been
in
business
since
1775
The
business
has
been
family
owned
for
seven
generations
The
candles
from
Ajello’s
are
well
known
for
their
beauty
and
quality
While
they
make
more
candles
now
than
in
1775
their
dedication
to
quality
and
to
customers
has
never
changed
The
Ajello
Candle
Company
was
founded
by
Rafael
Ajello
an
Italian
painter
He
was
also
a
beekeeper
so
he
tried
his
hand
at
using
bees
wax
to
create
candles
He
worked
hard
to
create
a
formula
that
worked
well
The
formula
combined
with
his
outstanding
artistic
ability
lead
to
the
birth
of
the
Ajello
Candle
Company
In
1785
the
company
earned
the
honor
of
creating
all
the
candles
for
the
Vatican
He
and
his
wife
ran
the
business
keeping
their
children
involved
in
the
processes
from
an
early
age
As
time
went
on
their
children
and
grandchildren
kept
the
business
running
as
well
as
passed
the
family
business
on
to
their
children
By
1862
the
company
had
established
itself
as
a
leader
among
the
candle
making
industry
They
had
also
added
perfumes
and
many
.
Share this
SUBSCRIBE OUR NEWSLETTER
SUBSCRIBE OUR NEWSLETTER
Join us for free and get valuable content delivered right through your inbox.
Related Post
