Re: Different external IP address for different "show my IP" pages!!!

[Elton]

> Suspected typo...that last line should read "outside the range of your
> router's DHCP server..."

I think GlowingBlueMist is right because if I try to reserve an IP
address outside the DHCP Servers range, it gives me an error "Invalid
IP address".
The range is set from 192.168.1.2 to 192.168.1.254 .
I have reserved 192.168.1.2 for my web server pc and 192.168.1.3 for
another home desktop.
192.168.1.1 is the router itself of course.

[Char Jackson]

On Tue, 21 Sep 2010 16:19:46 -0700 (PDT), Elton <eltoni.91@gmail.com>
wrote:

>> Suspected typo...that last line should read "outside the range of your
>> router's DHCP server..."
>
>I think GlowingBlueMist is right

No, my correction was right. See below.

>because if I try to reserve an IP
>address outside the DHCP Servers range, it gives me an error "Invalid
>IP address".

That's because you've set the entire subnet within the DHCP scope.
There's very little reason to do that. Scale it back.

>The range is set from 192.168.1.2 to 192.168.1.254 .

Try lowering the number of available DHCP addresses to 50 or so.
Perhaps a range of .100 to .150 would be appropriate, leaving you
plenty of room outside of the DHCP scope while staying within the
subnet.

>I have reserved 192.168.1.2 for my web server pc and 192.168.1.3 for
>another home desktop.
>192.168.1.1 is the router itself of course.

I assume you mean you reserved those IP's in the router. Since .2 and
..3 currently fall within the DHCP scope, they shouldn't be set static
on the respective PC's.

[Elton]

> Try lowering the number of available DHCP addresses to 50 or so.
> Perhaps a range of .100 to .150 would be appropriate, leaving you
> plenty of room outside of the DHCP scope while staying within the
> subnet.

I set the DHCP Server range to : 192.168.1.10 - 192.168.1.254

> I assume you mean you reserved those IP's in the router. Since .2 and
> .3 currently fall within the DHCP scope, they shouldn't be set static
> on the respective PC's.

I also added the .2 and .3 IP addresses to the reserved list and
ignored the warnings.
What is the effect of this because I see none?

[Char Jackson]

On Wed, 22 Sep 2010 04:18:47 -0700 (PDT), Elton <eltoni.91@gmail.com>
wrote:

>> Try lowering the number of available DHCP addresses to 50 or so.
>> Perhaps a range of .100 to .150 would be appropriate, leaving you
>> plenty of room outside of the DHCP scope while staying within the
>> subnet.
>
>I set the DHCP Server range to : 192.168.1.10 - 192.168.1.254

With over 240 addresses still reserved for DHCP, I see you're still
expecting a party. :-)

>> I assume you mean you reserved those IP's in the router. Since .2 and
>> .3 currently fall within the DHCP scope, they shouldn't be set static
>> on the respective PC's.
>
>I also added the .2 and .3 IP addresses to the reserved list and
>ignored the warnings.
>What is the effect of this because I see none?

If I'm understanding correctly, you've taken the .2 and .3 addresses
out of the DHCP scope, but interestingly you've added these two
addresses to the reserved list even though nothing can happen because
they are now out of the DHCP scope...so what is the effect, you ask?
Well, I assume the two PC's are still set to use DHCP, so I'm not sure
what will happen. On the one hand, it seems like they'll get new
(higher) addresses now that their current addresses are no longer in
scope, but on the other hand you've configured their addresses as
reserved, so I don't know how your router handles that type of
conflict.

There are multiple approaches, but what I do is set aside a few
addresses in the low range for the router and any PC's or other
devices that should have addresses that never change. I set static
addresses on those devices, then I configure the router to hand out a
relatively small range of DHCP addresses to any other PC's and devices
that visit the network.

You've taken a different approach. If you're going to leave the two
PC's out of the DHCP scope as they are now, then I would make their
addresses static. If your router supports DHCP reservations, and I
think you're saying it does, then perhaps lower the DHCP scope so that
they are once again within the scope. Even so, is there a reason why
you have such a large range of addresses within the DHCP scope?

[Elton]

> If I'm understanding correctly, you've taken the .2 and .3 addresses
> out of the DHCP scope, but interestingly you've added these two
> addresses to the reserved list even though nothing can happen because
> they are now out of the DHCP scope...so what is the effect, you ask?
> Well, I assume the two PC's are still set to use DHCP, so I'm not sure
> what will happen. On the one hand, it seems like they'll get new
> (higher) addresses now that their current addresses are no longer in
> scope, but on the other hand you've configured their addresses as
> reserved, so I don't know how your router handles that type of
> conflict.

The reserved IPs are mapped to the corresponding MAC addresses of the
PCs in the reserved IPs configuration page of the router.
The network cards are configured to obtain an IP address
automatically.
Even with the last changes in the DHCP Server IP range, the PCs still
are assigned with the correct IP addresses.

> There are multiple approaches, but what I do is set aside a few
> addresses in the low range for the router and any PC's or other
> devices that should have addresses that never change. I set static
> addresses on those devices, then I configure the router to hand out a
> relatively small range of DHCP addresses to any other PC's and devices
> that visit the network.
>
> You've taken a different approach. If you're going to leave the two
> PC's out of the DHCP scope as they are now, then I would make their
> addresses static. If your router supports DHCP reservations, and I
> think you're saying it does, then perhaps lower the DHCP scope so that
> they are once again within the scope. Even so, is there a reason why
> you have such a large range of addresses within the DHCP scope?

No there's no particular reason.
That configuration came with the router by default so I left it like
it is.
Only last night I changed the starting IP address from 192.168.1.2 to
192.168.1.4, following the advice of GlowingBlueMist, which I still
don't understand where the point of all that was?

Is there any particular reason why should I not leave a large range of
addresses within the DHCP scope like you say?

[GlowingBlueMist]

On 9/22/2010 3:07 PM, Elton wrote:
>> If I'm understanding correctly, you've taken the .2 and .3 addresses
>> out of the DHCP scope, but interestingly you've added these two
>> addresses to the reserved list even though nothing can happen because
>> they are now out of the DHCP scope...so what is the effect, you ask?
>> Well, I assume the two PC's are still set to use DHCP, so I'm not sure
>> what will happen. On the one hand, it seems like they'll get new
>> (higher) addresses now that their current addresses are no longer in
>> scope, but on the other hand you've configured their addresses as
>> reserved, so I don't know how your router handles that type of
>> conflict.
>
> The reserved IPs are mapped to the corresponding MAC addresses of the
> PCs in the reserved IPs configuration page of the router.
> The network cards are configured to obtain an IP address
> automatically.
> Even with the last changes in the DHCP Server IP range, the PCs still
> are assigned with the correct IP addresses.
>
>> There are multiple approaches, but what I do is set aside a few
>> addresses in the low range for the router and any PC's or other
>> devices that should have addresses that never change. I set static
>> addresses on those devices, then I configure the router to hand out a
>> relatively small range of DHCP addresses to any other PC's and devices
>> that visit the network.
>>
>> You've taken a different approach. If you're going to leave the two
>> PC's out of the DHCP scope as they are now, then I would make their
>> addresses static. If your router supports DHCP reservations, and I
>> think you're saying it does, then perhaps lower the DHCP scope so that
>> they are once again within the scope. Even so, is there a reason why
>> you have such a large range of addresses within the DHCP scope?
>
> No there's no particular reason.
> That configuration came with the router by default so I left it like
> it is.
> Only last night I changed the starting IP address from 192.168.1.2 to
> 192.168.1.4, following the advice of GlowingBlueMist, which I still
> don't understand where the point of all that was?
>
> Is there any particular reason why should I not leave a large range of
> addresses within the DHCP scope like you say?

No real reason not to have the larger range of DHCP address values. I
tend to limit mine as most sites I supported used fixed IP's and only
allowed limited DHCP access for temporary devices.

As for having the Fixed IP's be included inside the DHCP range, I have
seen too many routers where that causes problems. Many still try to
assign a DHCP value that is already in use by a Fixed IP computer
causing one or both computers to have problems connecting.

[Char Jackson]

On Wed, 22 Sep 2010 13:07:25 -0700 (PDT), Elton <eltoni.91@gmail.com>
wrote:

>> If I'm understanding correctly, you've taken the .2 and .3 addresses
>> out of the DHCP scope, but interestingly you've added these two
>> addresses to the reserved list even though nothing can happen because
>> they are now out of the DHCP scope...so what is the effect, you ask?
>> Well, I assume the two PC's are still set to use DHCP, so I'm not sure
>> what will happen. On the one hand, it seems like they'll get new
>> (higher) addresses now that their current addresses are no longer in
>> scope, but on the other hand you've configured their addresses as
>> reserved, so I don't know how your router handles that type of
>> conflict.
>
>The reserved IPs are mapped to the corresponding MAC addresses of the
>PCs in the reserved IPs configuration page of the router.
>The network cards are configured to obtain an IP address
>automatically.
>Even with the last changes in the DHCP Server IP range, the PCs still
>are assigned with the correct IP addresses.

The existing DHCP leases may not have expired yet, or have they? It'll
be interesting to see what happens. I still see it as a configuration
conflict.

>> There are multiple approaches, but what I do is set aside a few
>> addresses in the low range for the router and any PC's or other
>> devices that should have addresses that never change. I set static
>> addresses on those devices, then I configure the router to hand out a
>> relatively small range of DHCP addresses to any other PC's and devices
>> that visit the network.
>>
>> You've taken a different approach. If you're going to leave the two
>> PC's out of the DHCP scope as they are now, then I would make their
>> addresses static. If your router supports DHCP reservations, and I
>> think you're saying it does, then perhaps lower the DHCP scope so that
>> they are once again within the scope. Even so, is there a reason why
>> you have such a large range of addresses within the DHCP scope?
>
>No there's no particular reason.
>That configuration came with the router by default so I left it like
>it is.
>Only last night I changed the starting IP address from 192.168.1.2 to
>192.168.1.4, following the advice of GlowingBlueMist, which I still
>don't understand where the point of all that was?
>
>Is there any particular reason why should I not leave a large range of
>addresses within the DHCP scope like you say?

In my opinion, everyone has their own opinion, so there's very little
reason to do it one way versus another. The multiple ways all get the
job done, but in different ways. Some people use DHCP for everything,
some use a mix of DHCP and static, and others use static addresses for
everything and simply turn DHCP off.

In my own network, almost everything is static, but I do keep a small
DHCP range enabled as well.

[Elton]

> The existing DHCP leases may not have expired yet, or have they? It'll
> be interesting to see what happens. I still see it as a configuration
> conflict.

The PCs are rebooted, halted, powered off and powered on several times
throughout the day and they still preserve the chosen IPs. I think
that in theory, each time a PC is powered, the router would assign
them semi-random IPs (depending on the turn they are powered on), if
the IPs weren't reserved.
Since the PCs have always the predefined IPs no matter in what turn
they are powered on, could we safely assume that no configuration
conflict is ocurring in both configuration cases, where:
Configuration Case 1: The .2 and .3 IPs are included in the DHCP
server range, DHCP server range is 192.168.1.2 - 192.168.1.254, DHCP
server lease time is exactly 1 day;
Configuration Case 2: The .2 and .3 IPs are excluded from the DHCP
server range, DHCP server range is 192.168.1.4 - 192.168.1.254, DHCP
server lease time is exactly 1 day ?


> In my opinion, everyone has their own opinion, so there's very little
> reason to do it one way versus another. The multiple ways all get the
> job done, but in different ways. Some people use DHCP for everything,
> some use a mix of DHCP and static, and others use static addresses for
> everything and simply turn DHCP off.

I think you misunderstood me. I wasn't trying to confront opinions or
choose which is better than the other.
I simply want to know the logic behind the opinion and to learn the
technical mechanisms that make someones approach to solve my problem,
execute/effectuate in my case.

> In my own network, almost everything is static, but I do keep a small
> DHCP range enabled as well.

In my first paragraph of this reply, I showed you how my router's DHCP
server is configured.
The network cards in both my PCs are configured to automatically
obtain an IP address, so they are not statically configured.
The reserved IP adresses list/table in my router's DHCP server config
page, are mapped to their respective MAC addresses of the PCs network
cards.
As said above, both PCs, acquire in every case the predefined IP
addresses.

[Char Jackson]

On Wed, 22 Sep 2010 17:53:51 -0700 (PDT), Elton <eltoni.91@gmail.com>
wrote:

>In my first paragraph of this reply, I showed you how my router's DHCP
>server is configured.
>The network cards in both my PCs are configured to automatically
>obtain an IP address, so they are not statically configured.
>The reserved IP adresses list/table in my router's DHCP server config
>page, are mapped to their respective MAC addresses of the PCs network
>cards.
>As said above, both PCs, acquire in every case the predefined IP
>addresses.

Very interesting! Thanks.