All language subtitles for Free CCNA - DTP_VTP - Day 19 - CCNA 200-301 Complete Course

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In this video we will cover two Cisco proprietary
protocols, DTP, aka dynamic trunking protocol,

and VTP, VLAN trunking protocol.

As I said, they are Cisco proprietary, meaning
they were developed by Cisco and they only

run on Cisco devices.

DTP and VTP were removed from the CCNA exam
topics list for the new exam (200-301).

However, it’s important to know their function,
and you may still get questions about them

on the exam even though they are not on the
topics list.

So, what will we cover in this video?

Well, I already said it.

We will cover DTP, dynamic trunking protocol,
first.

DTP is a Cisco proprietary protocol that allows
switches to negotiate the status of their

switchports to be either access ports or trunk
ports, without manually configuring them.

Then we will cover VTP, VLAN trunking protocol.

VTP is another Cisco proprietary protocol
that allows you to configure VLANs on a central

switch, which then acts as a server that other
switches can synchronize to, so you don’t

have to configure VLANs on every single switch
in the network.

Also, make sure you watch until the end of
today’s quiz, as I will once again feature

a question from ExSim for CCNA, by Boson Software.

ExSim for CCNA is Boson’s set of practice
exams for the CCNA, and they are widely regarded

as the best practice exams to get you ready
for the real thing.

I used them myself for my CCNA and CCNP.

If you want to get a copy of ExSim, follow
the link in the video description.

Let’s go over some points about DTP.

DTP is a Cisco proprietary protocol that allows
Cisco switches to dynamically determine their

interface status (access or trunk) without
manual configuration.

Basically, two Cisco switches connected together
can form a trunk, but otherwise the interface

will automatically be an access port.

DTP is enabled by default on all Cisco switch
interfaces.

Once again, because it is a proprietary protocol,
this applies only to Cisco switches.

So far, we have been manually configuring
switchports using either SWITCHPORT MODE ACCESS

or SWITCHPORT MODE TRUNK.

If we use DTP, we don’t need to enter these
commands.

Now, for security purposes, manual configuration
is recommended.

DTP should be disabled on all switchports.

DTP can be exploited by attackers, and I’ll
talk more about network security later in

this course, but for now just know that it
should be disabled on all interfaces.

Let’s go straight into the CLI.

I’m in interface configuration mode here
on a Cisco switch, and I entered SWITCHPORT

MODE, followed by the question mark.

You can see the ACCESS and TRUNK options we
used before, but the one we’re going to

look at now is this one, DYNAMIC.

It says ‘set trunking mode to dynamically
negotiate access or trunk mode’.

That’s DTP.

So, I entered DYNAMIC and used the question
mark again.

There are two options, AUTO and DESIRABLE.

The only description given is ‘Set trunking
mode dynamic negotiation parameter to AUTO

or DESIRABLE’, which doesn’t really explain
their function.

So, let me explain each of these modes.

A switchport in DYNAMIC DESIRABLE mode will
actively try to form a trunk with other Cisco

switches.

It will form a trunk if connected to another
switchport in the following modes: switchport

mode trunk.

switchport mode dynamic desirable, or switchport
mode dynamic auto.

Let’s see how that works.

SW1 and SW2 are connected via their G0/0 interfaces.

SW1’s G0/0 interface is in DYNAMIC DESIRABLE
MODE.

SW2’s G0/0 interface is manually configured
as a trunk.

So, these two switches will both agree to
operate as trunks.

Here is a new command, SHOW INTERFACES G0/0
SWITCHPORT.

These are just the first few lines of output,
I will show you the others later.

It says switchport: enabled, because it is
a layer 2 port.

If we want to configure a routed port with
the ‘no switchport’ command, this would

display differently.

The administrative mode is dynamic desirable.

Administrative mode is what we actually configured
on the interface, and then below it, operational

mode, displays whether it is a trunk or access
port.

Because SW2’s interface is a trunk, SW1’s
interface became a trunk as well, thanks to

DTP negotiation.

Here on SW2 you can see that both the administrative
mode AND operational mode are trunk.

Now both interfaces are configured in dynamic
desirable mode.

So, they will both form a trunk.

The output of SHOW INTERFACES SWITCHPORT is
the same on SW1, and this time SW2 also has

an administrative mode of ‘dynamic desirable’,
but once again the operational mode is trunk,

because both switches are actively using DTP
to try to form a trunk.

Even if manually configured as a trunk, an
interface still sends DTP frames out of the

interface.

This time SW2’s interface is configured
in dynamic auto mode.

A switchport in dynamic auto mode does not
actively try to form a trunk.

It’s more passive.

It will tell SW1 ‘if you want to form a
trunk, I’ll form a trunk, but I’m not

going to actively try to form a trunk with
you.’

However, because SW1 is in dynamic desirable
mode, once again a trunk will be formed.

SW1’s SHOW INTERFACES SWITCHPORT output
is the same, and SW2’s shows an administrative

mode of dynamic auto, and again an operational
mode of trunk.

One more example: SW2’s interface is now
manually configured as an access port with

the SWITCHPORT MODE ACCESS command.

SW1 is actively trying to form a trunk, but
since SW2 is manually configured in access

mode, the trunk will not form, and both will
operate as access ports in the default VLAN,

which is VLAN 1.

The output of SHOW INTERFACES SWITCHPORT on
SW1 now shows an operational mode of static

access.

What does ‘static access’ mean?

‘static access’ means an access port that
belongs to a single VLAN that doesn’t change

(unless you configure a different VLAN).

There are also ‘dynamic access’ ports,
in which a server automatically assigns the

VLAN depending on the MAC address of the connected
device.

But this is out of the scope of the CCNA, you
don’t need to learn about dynamic access

ports, I just wanted to clarify what ‘static
access’ means.

Now, on SW2’s g0/0 interface both the administrative
and operational modes are static access.

Okay, now you’ve learned about dynamic desirable
mode and seen that an interface in dynamic

desirable mode will use DTP negotiation to
form a trunk if the connected interface on

the other device is in trunk, dynamic desirable,
or dynamic auto mode.

However, if the other interface is in access
mode, it will not form a trunk, it will be

an access port.

Now let’s look at dynamic auto mode.

A switchport in dynamic auto mode will NOT
actively try to form a trunk with other Cisco

switches, however it will form a trunk if
the switch connected to it is actively trying

to form a trunk.

It will form a trunk with a switchport in
the following modes: switchport mode trunk,

or switchport mode dynamic desirable.

So, SW1’s G0/0 interface is configured in
dynamic auto mode, and SW2’s is manually

configured as a trunk.

Therefore, DTP negotiation will cause them
to form a trunk link.

Here you can see the administrative mode of
dynamic auto and operational mode of trunk,

whereas on SW2 both are trunk.

Now, we already saw what happens when a switchport
in dynamic auto mode is connected to a switchport

in dynamic desirable mode, they form a trunk.

So, let’s look at two switchports in dynamic
auto mode.

Neither is actively trying to form a trunk,
so both operate as access ports in the default

VLAN, VLAN1.

And they have the same output for the SHOW
INTERFACES SWITCHPORT command, administrative

mode of dynamic auto and operational mode
of static access.

Next up, dynamic auto and access mode.

As you can probably guess, this will result
in both interfaces operating as access ports.

Here is the output of SHOW INTERFACES SWITCHPORT
on each switch.

Now, you may wonder what happens if a manually
configured trunk is connected to a manually

configured access port?

Well, since both are manually configured,
they are forced to operate mismatched in trunk

and access modes.

Here is the output of SHOW INTERFACES SWITCHPORT
for each.

However, this configuration does not work,
it should result in an error, and traffic

will not pass between these switches.

Here’s a chart summarizing the resulting
operational mode given two administrative

modes.

For example, a switchport in dynamic desirable
mode will form a trunk with an interface in

any administrative mode except access.

Pause the video here if you want to take a
look at this table.

Now, one more important point.

DTP will not form a trunk with a router, PC,
etc.

The switchport will be in access mode.

So, if you want to configure router on a stick,
you must manually configure the interface

connected to the router as a trunk, you cannot
put it in dynamic desirable mode and expect

it to become a trunk.

Let me cover a few more points about DTP.

On older switches, switchport mode dynamic
desirable is the default administrative mode.

They will actively try to form trunk links.

However, on newer switchers, switchport mode
dynamic auto is the default administrative

mode.

You can disable DTP negotiation on an interface
with this command: switchport nonegotiate.

If you use this command, the interface will
stop sending DTP negotiation frames.

By the way, configuring an access port with
switchport mode access also disables DTP negotiation

on an interface.

It will also stop sending DTP frames.

If you manually configure an interface in
trunk mode, however, it does not stop it from

sending DTP frames, unless you also issue
the SWITCHPORT NONEGOTIATE command above.

As I said before, it is recommended that you
disable DTP on all switchports and manually

configure them as access or trunk ports.

Now let me talk about trunk encapsulation negotiation.

Switches that support both dot1q and ISL trunk
encapsulations can use DTP to negotiate the

encapsulation they will use.

This negotiation is enabled by default, as
the default trunk encapsulation mode is: switchport

trunk encapsulation negotiate.

I mentioned this in a previous video on VLANs.

If you want to manually configure a trunk
interface on a switch that supports both dot1q

and ISL, you must first change the encapsulation
mode to dot1q or ISL, you can’t leave it

in negotiate mode.

ISL is favored over dot1q, so if both switches
support ISL it will be selected.

By the way, the DTP frames that DTP uses to
negotiate are sent in VLAN1 when using ISL,

or in the native VLAN when using dot1q.

The default native VLAN is VLAN1, however,
so unless you change the native VLAN they

will be sent in VLAN1 for dot1q also.

To show you this negotiation of trunking encapsulation,
here is a little more of the output from SHOW

INTERFACES SWITCHPORT.

I set the interfaces on both switches to dynamic
desirable mode so they would form a trunk.

Notice that the default trunking encapsulation
mode of negotiate results in an operational

trunking encapsulation of ISL.

By the way, this field down here, negotiation
of trunking, shows whether DTP is enabled,

whether the interface is sending DTP frames
or not.

If the interface is in dynamic desirable,
dynamic auto, or trunk mode, this will be

on.

If it’s in access mode, or if you use the
switchport nonegotiate command I showed you

before, this will be off.

Okay, that was a good deal of information
about DTP.

I’m quite sure that you won’t need any
more information than that for the CCNA when

it comes to DTP.

If you need extra review, watch the section
again, try out the configurations in packet

tracer yourself, and then try my packet tracer
practice lab which will be in the next video.

Next, let’s move on to today’s second
topic, VTP, VLAN Trunking Protocol.

VTP allows you to configure VLANs on a central server switch, and other switches (called

VTP clients) will synchronize their VLAN database
to the server.

It is designed for large networks with many
VLANs, so that you don’t have to configure

each VLAN on every single switch.

However, like DTP it is rarely used, and it
is recommended that you do not use it.

I will show you one reason why it is recommended
that you do not use it later.

There are three versions of VTP, 1, 2 and
3.

Most modern Cisco switches support all three,
but older switches might only support 1 and

2.

I will talk about some differences in each
version as we go.

There are three VTP modes that a switch can
operate in: server, client, and transparent.

Cisco switches operate in VTP server mode
by default.

Let’s talk about the different VTP modes.

First up, VTP servers. They can add, modify, and
delete VLANs.

As I said, Cisco switches operate in VTP server
mode by default, so you can modify the VLAN

database on Cisco switches by default.

They store the VLAN database in non-volatile
RAM, also called NVRAM.

This means the VLAN database is saved even
if the switch is turned off or reloaded.

VTP servers will increase the REVISION NUMBER
every time a VLAN is added, modified, or deleted.

This revision number is a very important part
of VTP.

It’s what VTP uses to determine the newest
version of the VLAN database, the version

that the switches will synchronize to.

VTP servers will advertise the latest version
of the VLAN database on trunk interfaces and

the VTP clients will synchronize their VLAN
database to it.

So, VTP advertisements aren’t sent on access
ports, only on trunk ports.

Here’s another important point: VTP servers
also function as VTP clients.

What does that mean?

It means that a VTP server will synchronize
to another VTP server with a higher revision

number, because the highest revision number
is considered the newest, most accurate version

of the VLAN database.

Now let’s talk about VTP clients a little.

VTP clients cannot add, modify, or delete
VLANs.

If you try to add, modify, or delete a VLAN
in the CLI, the command will be rejected.

VTP clients do not store the VLAN database
in NVRAM, however in the newest VTP version,

VTPv3, they do.

VTP clients will synchronize their VLAN database
to the server with the highest revision number

in their VTP domain.

I will talk about VTP domains soon.

Finally, VTP clients will advertise their
VLAN database, and forward VLAN advertisements

to other clients over their trunk ports.

Okay, that’s enough information for now.

I will talk about the third VTP mode, VTP
transparent, later.

So let’s look at how VTP works.

These are four switches, and I’ve configured
all of their interfaces as trunks, so they

will send and receive VTP advertisements between
each other.

Here is the output of a very useful command,
SHOW VTP STATUS, on SW1.

All of these switches have the default configuration,
so their output will be mostly the same.

Let’s look at some of these fields.

These fields here shows that the switch is
capable of running VTP version 1, 2, or 3,

but it is running version 1 at the moment,
the default.

Notice that there is no domain name.

By default the domain name is NULL, there
is no domain name.

If we want VTP to synchronize among these
devices, we will need to configure them all

with the same VTP domain name.

Now look down here.

You can see the default VTP operating mode
of server.

Notice the maximum number of VLANs supported
locally is 1005.

This is because VTP version 1 and version
2 do not support the extended VLAN range of

1006 to 4094.

Only version 3 supports them, so if you want
to use the extended VLAN range you’ll need

to use VTP version 3.

The number of existing VLANs is 5, those are
the VLANs that exist by default on the switch,

1 and 1002,3,4,and 5.

Finally, look at the configuration reivision
number.

It is 0 at the moment.

If I add, modify, or delete a VLAN this will
increase to 1, and SW1 will advertise this

to VTP clients in the same domain.

It will also update its own VLAN database
if it receives a VTP advertisement with a higher

revision number, because VTP servers function
as VTP clients also.

So, I used the command VTP DOMAIN CISCO to
change SW1’s VTP domain name to cisco.

I then made a vlan, VLAN10, and named it engineering.

So, because I added a VLAN, if I do SHOW VTP
STATUS again, we should see that the revision

number has increased.

You can now see that the VTP domain name has
changed to Cisco, the number of existing VLANs

is 6, and the revision number has increased
to 1.

Now let’s go check on the other switches.

Okay, so something interesting has occurred.

Without any configuration, SW2 has changed
its domain name to cisco and updated its VLAN

database to match SW1’s, with a revision
number of 1.

If a switch with no VTP domain (or domain NULL)
receives a VTP advertisement with a VTP domain

name, it will automatically join that VTP
domain.

So, SW2 automatically joined the domain cisco.

As I said before, If a switch receives a VTP
advertisement in the same VTP domain with

a higher revision number, it will update its
VLAN database to match.

If I do SHOW VLAN BRIEF on SW2 now, you can
see that VLAN10, with the name ‘engineering’,

was added.

Here you can see that the advertisements were
passed along to SW3 and SW4 as well, and they

joined the domain and updated their VLAN database
as well.

Since you’ve seen how VTP sync works, let
me introduce one danger of VTP:If you connect

an old switch with a higher revision number
to your network (and the VTP domain name matches),

all switches in the domain will sync their
VLAN database to that switch.

This could cause all of the hosts on your
network to instantly lose connectivity, because

the switches could sync to a totally different
VTP database, and the VLANs you were using

could disappear.

This is one reason why VTP is usually not
used in modern networks.

Just to demonstrate that, let’s say this
VTP domain Cisco has a revision of

5, and VLANs 1, 10, 20, 30, and 40.

Then you take an old switch your company used
to use, to add to the network, however it

has a revision number of 50, and VLANS1, 99,
and 220.

It will send VTP advertisements with this
revision number, which will be forwarded throughout

the domain.

All of these switches will update their VLAN
database to match, and all hosts in VLANs

10,20,30, and 40 will suddenly lose connectivity.

Next let me talk about VTP transparent mode.

Switches in VTP transparent mode do not participate
in the VTP domain, they do not sync their

VLAN database to the VTP server.

VTP transparent mode maintains its own independent
VLAN database in NVRAM.

It can add, modify, or delete VLANs, but they won’t
be advertised to other switches.

Although it doesn’t sync its VLAN database,
it will forward VTP advertisements over its

trunk ports, if the VTP advertisement is in
the same domain as it, but it won’t advertise

its own VLAN database.

So let’s compare the functionality of server,
client, and transparent mode switches.

I set SW2 to client mode with the command
VTP MODE CLIENT.

Afterward, I tried to create VLAN20 on the
switch, but as you can see I was rejected,

because SW2 is now in client mode.

Then I set SW3 to transparent mode with VTP
MODE TRANSPARENT.

Also, to show you that a transparent mode
switch won’t forward advertisements if its

in a different domain, I changed the domain
name to juniper.

So, I created VLAN 20, named sales, on SW1
and you can see it appears in the output of

show vlan brief.

Then I did show vtp status, and you can see
that the configuration revision number is

4.

It should be 2 I think, but I made a few other
changes as I was trying things out in the

lab for this video.

Anyway, let’s see check out SW2.

As you can see, the VTP client SW2 has indeed
added VLAN20 to its VLAN database, and it

now has the same revision number, 4.

How about the transparent switch, SW3?

As expected, on the transparent switch SW3,
VLAN20 was not added, and now it has a revision

number of 0.

Changing the VTP domain to an unused domain
will reset the revision number to 0.

Changing the VTP mode to transparent will
also reset the revision number to 0.

So, if you’re going to plug an old switch
with a high revision number into a network

that uses VTP, make sure to reset the revision
number with one of these methods first, so

it doesn’t overwrite your network’s VLAN
configurations.

Now, the question is whether SW4 will have
added VLAN20 to its VLAN database.

Remember, SW3 is in transparent mode in a
different domain, so it shouldn’t forward

the VTP advertisements to SW4.

Indeed, SW4 does not have VLAN20, and it is
still on revision number 3.

So, what can we do to make SW3 start forwarding
the VTP advertisements to SW4?

If we change the VTP domain on SW3 back to
Cisco, it should start forwarding advertisements

to SW4, even though SW3 itself won’t sync
its own VLAN database based on those advertisements.

So, I changed the VTP domain on SW3 back to
cisco.

I also created some new VLANs on SW1 to increase
the revision number and send more advertisements,

by the way, and now you can see that SW3 did
indeed forward the advertisements to SW4,

and SW4 synced its VLAN database to SW1 and
SW2.

Finally, I’ll just talk about VTP version
a little bit.

To change the VTP version, use the VTP VERSION
command.

Changing the VTP version increases the revision
number, by the way, and advertisements with

this new revision number will be sent.

Other servers and clients will then sync and
start operating in version 2 as well.

For example here is SW4, it is now running
version 2 and has a revision number of 13,

just like SW1.

As for the difference between VTP version
1 and version 2, here is a quote directly

from Cisco: VTP V2 is not much different than
VTP V1.

The major difference is that VTP V2 introduces
support for Token Ring VLANs.

If you use Token Ring VLANs, you must enable
VTP V2.

Otherwise, there is no reason to use VTP V2.

Token ring is an old technology, so really
there is no reason to use version 2.

As for version 3, it has quite a few differences
and new features, but it’s certainly beyond

the scope of the CCNA, so we’ll leave it
here.

Okay here’s the first slide on VTP again.

To be honest, there is still lots more I can
talk about regarding VTP, but I will leave

it at that for this course.

Again, it isn’t on the exam topics list,
but you may get some basic questions about

VTP and its purpose, so I wanted to tell you
about some of its functions.

If you learn and remember the information
I’ve given you in this video regarding VTP,

that should be more than enough for the CCNA
exam.

Basically, just know the purpose of VTP, the
differences between server, client, and transparent

mode, know that switches operate in server
mode by default and that servers operate as

clients too, and know about revision numbers.

If you know all of that, you should be fine.

So before moving on to today’s quiz let’s
review what we covered.

We looked at DTP first, which is a protocol
that allows Cisco switches to form trunk connections

with other Cisco switches, without manual
configuration.

However, it’s recommended that you disable
this protocol for security purposes.

Then we looked at VTP, another Cisco proprietary
protocol that allows you to configure VLANs

on switches that operate as central VTP servers,
which then advertise their VLAN database,

and VTP client switches sync their database
to it.

Note that VTP only syncs the VLAN database,
you still have to configure the interfaces

on each switch separately, for example SWITCHPORT
ACCESS VLAN 10, etc.

VTP does not automatically assign interfaces
to VLANs.

Both of these protocols are no longer on the
exam topics list, but you should know about

them and their basic functions, you may get
questions about them on the exam.

Okay let’s move on to today’s quiz.

As a bonus, I will also feature one practice
question from Boson’s ExSim for CCNA, a

set of practice exams I highly recommend you
get to prepare for your CCNA exam.

Check out ExSim via the link in the video
description.

Okay, let’s go to question 1 of today’s
quiz.

SW1 and SW2 are connected, are both new switches,
and the connected interfaces are operating

as access ports.

However, SW2’s power supply fails so you
temporarily replace SW2 with an old spare

switch.

You reset the configuration before connecting
it to SW1, but when you connect it you notice

that a trunk is formed between the two switches.

What could be the cause?

A, interfaces on old switches default to switchport
mode trunk.

B, interfaces on old switches default to switchport
mode dynamic desirable.

Or C, access ports are a feature of newer
switches.

Pause the video to think about your answer.

The answer is B, interfaces on old switches
default to switchport mode dynamic desirable.

Newer switches default to dynamic auto.

So, in this case SW1’s interface is probably
in dynamic auto mode, and the old replacement

switch’s interface is probably in dynamic
desirable mode, so they would form a trunk.

Let’s go to question 2.

SW1 is connected to SW2, and SW2 is connected
to SW3.

You want SW2 to forward SW1’s VLAN database
information to SW3, but you don’t want SW2

to synchronize its VLAN database to SW1.

Which command should you use on SW2?

A, vtp mode transparent.

B, vtp transparent mode.

C, vlan mode transparent.

Or D, vtp mode client.

Pause the video to think about your answer.

The answer is a, vtp mode transparent.

A switch in VTP transparent mode will forward
VTP advertisements, but it won’t sync its

VLAN database to the VTP server.

It also won’t advertise its own VLAN database. Let's go to question 3.

What are two methods to reset a switch’s
VTP revision number to 0?

(Choose two.

Each answer is a complete solution).

A, change the VTP domain to an unused domain
name.

B, change the switch to VTP server mode.

C, change the switch to VTP transparent mode.

Or D, use the VTP RESET command.

Pause the video to think about your answer.

The answers are A, change the vtp domain to
an unused domain name, and C, change the switch

to VTP transparent mode.

Either of these methods will reset the revision
number to 0.

This is useful if adding a switch with a higher
VTP revision number to a network.

Okay, now let’s go to today’s Boson ExSim
question.

For today's Boson ExSim practice question,
I've selected not a multiple choice question,

but a drag-and-drop question.

So this is about DTP, Dynamic Trunking Protocol.

Select the VLAN trunking operational modes
from the left, access, trunk and also misconfig,

and drag them to the resulting trunking configuration.

So here we have one end of the connection,
one switch interface.

And then the other switch, the other end.

Access, dynamic auto, dynamic desirable, or
trunk.

Okay, so see if you can complete this chart
on your own.

Pause the video if you want to try it.

Okay, so let's walk through the answers.

So, here on one end of the connection, access
mode.

Manually configuring a switch port in access
mode turns off DTP negotiation.

It won't form a trunk port, no matter what.

So, two access ports will result in an operational
mode of access.

Access and dynamic auto, same thing.

So, dynamic auto can form a trunk but it won't
actively try to form a trunk unless the other

end is trying to form a trunk.

So, that will be access.

Access and dynamic desirable.

Although this end is trying to form a trunk,
this end will not, so that is access.

Now, access and trunk that is a misconfig.

Do not do this in a real network.

You can try it out in a lab to see what happens,
but do not do it in a real network.

You will encounter problems.

Dynamic auto and access, well we just saw
that here.

That will be an access port.

Dynamic auto and dynamic auto.

Neither is actively trying to form a trunk,
so that will be access.

Dynamic auto and dynamic desirable.

This end is actively trying to form a trunk,
so they will form a trunk.

Same thing, dynamic auto and trunk will form
a trunk.

Even if you manually configure 'switchport
mode trunk', DTP is still running and this

end will actively try to form a trunk with
the other end.

And since it is dynamic auto, they will form
a trunk.

Okay, dynamic desirable and access, that will
result in access.

This end will refuse to become a trunk.

Dynamic desirable and dynamic auto, that will
form a trunk.

Two dynamic desirables definitely form a trunk.

And this one as well, trunk.

Okay, next, moving on to trunk on this end.

Trunk and access, again that is a misconfig.

Don't do this in a real network.

Trunk and dynamic auto will form a trunk.

Trunk and dynamic desirable, of course.

And, of course, trunk and trunk also will
form a trunk.

So once you've finished, click on 'done'.

And then click on 'show answer'.

Now, if you don't want to check the answer
yet you can click on next to go to the next

question in the practice exam.

But let's see if I got the correct answer.

And, I did.

Okay, here is Boson's explanation, you can
read it if you want.

And there are also references here.

The official cert guide by Wendell Odom, volume
1 chapter 8: Implementing Ethernet VLANs.

And some additional reading from Cisco.

I will link some reading from Cisco in the
video description, by the way.

And this category shows which category of
the exam topics list this question is from.

This is from the 'network access' category.

Okay, so that's today's ExSim practice question.

If you want to get a copy of ExSim for yourself,
and I highly recommend you do, they are fantastic

practice exams, please follow the link in
the video description.

There will be supplementary materials for
this video.

There will be a review flashcard deck to use
with the software ‘Anki’.

Download the deck from the link in the description.

There will also be a packet tracer practice
lab to help you practice the configurations

from this video.

That will be in a separate video.

Before finishing today’s video I want to
thank my JCNP-level channel members.

Thank you to Samil, velvijaykum, C Mohd, Johan,
Mark, Aleksa, Miguel, Yousif, Boson software,

the creators of ExSim, by the way, Sidi, Magrathea,
Devin,Charlsetta, Lito, Yonatan, Mike, Aleskander,

and Vance.

Sorry if I pronounced your name incorrectly,
but thank you so much for your support.

One of you is displaying at Channel failed
to load, if this is you please let me know

and I’ll see if YouTube can fix it.

This is the list of JCNP-level members at
the time of recording by the way, if you signed

up recently and your name isn’t on here
don’t worry, you’ll definitely be in the

next video.

Thank you for watching.

Please subscribe to the channel, like the
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