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Home > Archive > microsoft.public.cert.exams.mcse > August 2002 > DHCP Question for 70-216
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DHCP Question for 70-216
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| Karim M Ladhu 2002-08-13, 5:23 pm |
| Studying for 70-216 - last core for MCSE 
However, I am a bit confused about how a DHCP server
handles multiple scopes - how does it decide which one to use?
In the event where there is a DHCP Relay Agent which adds
it's address and subnet mask to the request - I understand the
DHCP server can figure out which scope to use, but what if
the request comes from the same network as the DHCP server
without passing through a DHCP Relay Agent???
Which scope would it use? Would it check its own default
gateway information and work it out like that?
Is it different in a Superscope? How does a DHCP server
decide which scope it is to use in a Superscope?
How are multiple Superscopes handled?
I am using the Syngress / Osborne book and it's not
very explicit about this...
Thanking you in advance,
Karim Ladhu
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| William Korvine 2002-08-13, 8:23 pm |
| I'm using the same books. They seem mostly ok. I havn't passed
that exam yet, so some of this might be wrong.
William Korvine
"Karim M Ladhu" <contactme@karimladhu.co.uk> wrote in news:J4g69.174673
$yc3.7547916@bin4.nnrp.aus1.giganews.com:
> Studying for 70-216 - last core for MCSE
>
> However, I am a bit confused about how a DHCP server
> handles multiple scopes - how does it decide which one to use?
I had the same problem and some kind soul on this group
explained it to me. For DHCP to work, the network interface
must have a static IP address. For non-relayed DHCP requests,
DHCP assigns from the scope that includes the static IP address
of the adapter on which the request came in.
In my case, I have two adapters (and thus two subnets on my LAN).
Adapter 'Vectra', 192.168.5.1
Adapter 'Notebook', 192.168.7.1
DHCP requests coming in on 'Vectra' are assigned from the scope
also called 'Vectra' with the range 192.168.5.1 to 192.168.5.254
(with 192.168.5.1 excluded because it's been assigned to the
adapter). Requests coming in on 'Notebook' are assigned from scope
'Notebook", 192.168.7.1 to 192.168.7.254 with 192.168.7.1 excluded.
> In the event where there is a DHCP Relay Agent which adds
> it's address and subnet mask to the request - I understand the
> DHCP server can figure out which scope to use, but what if
> the request comes from the same network as the DHCP server
> without passing through a DHCP Relay Agent???
Of course, requests coming through a relay agent include
the IP address of the agent. DHCP will assign from the scope
which includes that address.
> Which scope would it use? Would it check its own default
> gateway information and work it out like that?
AFAIK, no.
> Is it different in a Superscope? How does a DHCP server
> decide which scope it is to use in a Superscope?
>
> How are multiple Superscopes handled?
I believe that a super-scope permits you to have multiple
scopes associated with the same network adapter. As long
as the adapter's address is within one of the scopes, DHCP
can assign addresses from any of the scopes.
Frex, suppose my 'Vectra' subnet suddenly sprouts 300 more
computers. My 'Vectra' scope only has room for 254 (192.168.5.1
to 192.168.5.254). I need to add another scope, say 192.168.6.1
to 192.168.6.254). But this new scope will not be used
because my network adapter (192.168.5.1) is not within
that scope. Solution: Create a super-scope which includes
both of them. Now DHCP will assign from either.
BTW, I didn't know this until you asked, so I learned
something too. I hope I'm right.
> I am using the Syngress / Osborne book and it's not
> very explicit about this...
It seems a pretty good book so far to me.
> Thanking you in advance,
Hope this helps.
> Karim Ladhu
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| 70-228 2002-08-14, 2:23 am |
| "William Korvine" <korvine@hotmail.com> wrote in message
> Frex, suppose my 'Vectra' subnet suddenly sprouts 300 more
> computers. My 'Vectra' scope only has room for 254 (192.168.5.1
> to 192.168.5.254). I need to add another scope, say 192.168.6.1
> to 192.168.6.254). But this new scope will not be used
> because my network adapter (192.168.5.1) is not within
> that scope. Solution: Create a super-scope which includes
> both of them. Now DHCP will assign from either.
You might want to think about a superscope on Vectra composing the
10.0.1.0/24 scope and the 10.0.2.0/24 scope....
PS. I wouldn't worry too much about Superscopes. Rarely used.
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| Karim M Ladhu 2002-08-14, 3:23 am |
| Thanks!
You've been a great help... now I can sleep at night
Karim.
"70-228" <ToldePD@ariz.ka> wrote in message
news 8o69.95227$0b6.954188@news.easynews.com...
> "William Korvine" <korvine@hotmail.com> wrote in message
> > Frex, suppose my 'Vectra' subnet suddenly sprouts 300 more
> > computers. My 'Vectra' scope only has room for 254 (192.168.5.1
> > to 192.168.5.254). I need to add another scope, say 192.168.6.1
> > to 192.168.6.254). But this new scope will not be used
> > because my network adapter (192.168.5.1) is not within
> > that scope. Solution: Create a super-scope which includes
> > both of them. Now DHCP will assign from either.
>
> You might want to think about a superscope on Vectra composing the
> 10.0.1.0/24 scope and the 10.0.2.0/24 scope....
>
> PS. I wouldn't worry too much about Superscopes. Rarely used.
>
>
>
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