Changing the IP scope

[edberlot]

We are slowly but surely running out of IP space (poor decision was made a few years back) and we are slowly migrating to a Class B address.

Right now my PC's IP would be on the class B address (10.5.x.x) while my DNs Servers are on 192.168.5.100 and 101

Routing between the 2 networks is handled by the firewall, so that works like a charm.

This is where I get little lost?

Obviously using a different IP space my DNS server at 192.168.0.100 is not going get updated.

So 2 questions

1) Would it make sense to create another DNS server and forward any requests outside of the 10.5.x.x address space to the 192.168.0.100 server

2) If I don't do #1 what are the ramifications to my workstations?

Thanks

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[Meinolf Weber [MVP-DS]]

Hello Ed,

If you use 10.5.x.x with a subnet mask 255.255.0.0 (65534 clients) and running
out of addresses, i would use a new subnet and setup routing correct and
your DNS servers should be able to support them also.

Personal i ouwld make the subnet smaller, you have a real big broadcast domain,
with a lot of not needed traffic.

Best regards

Meinolf Weber
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[Ace Fekay [MCT]]

"Ed Berlot" wrote in message
news:20091112111...@tvchannelzero.com...

This is not really a DNS question, rather a networking question.

Nonetheless, you can simply use a /23 (255.255.254.0) which will provided up
to 512 hosts, instead of your current /24 (255.255.255.0) that is currently
providing upto 256 hosts. If you need more hosts, such as up to 1024, you
can change the subnet to a /22 (255.255.252.0), this way you don't have to
change the IP scheme, just the subnet. Everything can keep their current IP,
but you would increase the DHCP scope. You would also change the reverse
zone subnet.

Other than that, if you are already routing between two subnets (because the
DNS servers are somewhere else), no change required.

--
Ace

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[J de Boyne Pollard]

EB> This is where I get little lost?

Yes. (-: What you wrote next shows this:

EB> Obviously using a different IP space my DNS server at

192.168.0.100  is not going get updated.

No. There's nothing obvious about this, because it isn't actually
true.

It's fairly simple, and M. Fekay covers most of it. If you can route
all of the IP traffic around happily, then there really isn't much of
a DNS server issue here at all. The _only_ place where DNS comes into
it is the address-to-name mappings published by your content DNS
server, and there are really two basic issues:

* You need to ensure that Dynamic DNS Update continues to work with
the new IP address information, as your machines are granted DHCP
leases. But only if you are using DHCP in the first place.
* You need to ensure that your content DNS server serves up the
appropriate reverse-lookup "zone" for your new IP address space.

You don't need additional DNS servers. You don't need forwarding
proxy DNS service. The IP address that a content DNS server provides
service upon has nothing to do with _what content it serves_. The
only issue here for DNS is DNS _database content_. As you yourself
said, you've got the IP traffic on the network "working like a charm".

So make sure that you have a "10.in-addr.arpa." zone, and that you've
got it properly configured so that your DHCP server, if you have one,
can update it with address-to-name mappings as it hands out and
revokes leases. If you don't have a DHCP server, and are just using
static mappings, make sure that you've populated the database with
them.

Oh, and by the way: Don't use a "5.10.in-addr.arpa." zone.

<URL:http://homepage.ntlworld.com./jonathan.deboynepollard/FGA/dns-
private-address-split-horizon.html#Subnets>

You've made the mistake of not planning for future expansion once.
Don't make it again. (-: You'll be a good neighbour to the rest of
Internet if you _don't_ allow "*.10.in-addr.arpa." DNS queries to leak
over your borders, moreover.