Question

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DHCP Scope

By gautam.sanjog ·
Hi,

Currant setup , I have with server 2003 DHCP + DNS setup as listed.
Scope
192.168.100.1 to 192.168.100.254
255.255.255.0 - Sub net Mask
192.168.100.1 ( Router ??? Sonic wall ) ( Default Gateway for All member server + Client )
192.168.100.8 ( Domain server + ADC )

Issue : Problem of Dwindling IP addresses ( this scope All IP useed it's give error of 90 % IP used )

Questions :
how to setup 2nd scope with new IP range E.g. 192.168.101.1 to 254 ? sub net same ? how to setup like not make any major change in other setup & get new IP range in exits setup.

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All Answers

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Three possibilities

by cmiller5400 In reply to DHCP Scope

1. You didn't specify the DHCP lease time, set it shorter for machines that may be off, thus freeing up IP's

2. You add a another subnet to your network, this will involve either a layer 3 switch or a router.

3. You change the subnet mask to give you more hosts per network.

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Reponse To Answer

by gautam.sanjog In reply to Three possibilities

hi can you guide me now to do in revised setup
In-short Issue of 192.168.100.1 to 192.168.100.254 Scope Range it's Assigned to pc + servers & some of static device. Now needs to Add some more PC in same network but DHCP server not able to give IP Due to All IP used .. what is solution

setup detail
DHCP server with server 2003 Operating System
Server IP - 192.168.100.8 ( it's with DHCP & DNS )
DHCP server Scope : 192.168.100.1 to 192.168.100.254
sub net Mask . 255.255.255.0
Default gateway 192.168.100.1 ( sonicwall router )
exude IP 192.168.100.1 to 192.168.100.70
sonic wall Router : 192.168.100.1

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I see problems here

by Charles Bundy In reply to DHCP Scope

Are you saying you have assigned static IPs within the range of your DHCP scope? E.G.

Router is 192.168.100.1 & server is 192.168.100.8.

Try setting your subnet to 255.255.254.0 and DHCP leased range to 192.168.101.1-254 and leave 192.168.100.x for static purposes.

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DHCP Scoping

by will In reply to DHCP Scope

Greetings,

DHCP is one of the simplest tools to use, but equally once one steps outside of the 'typical' or 'default' settings, it can be cumbersome. I have had some pain in this area, so i went out and dug as deep as possible.

Here are a couple of things of importance:

1. DHCP is based on bootp.
2. The machine, once it receives an IP, doesn't wait until the end of the lease to get a new one. the machine will contact the server multiple times as the lease expires - you can get a better explanation on a wiki elsewhere, but understand it does do so.
3. DHCP, unless the machine is on the same subnet, is typically proxied by the router.

the process . . .
A machine yells "I need an address."
The router hears it, picks it up, forwards it to the proper server, waits for the address and delivers it back to the machine.
~And it happens quickly~

First, i would check the scope.
It appears that you have reserved addresses that are covered in a static form, but also available to machines needing an address.
Remove all of the static IPs by creating a subnet template that excludes a certain amount of addresses.
This will be company-specific as well as subnet-specific.
Since we will be making the template, lets jump ahead and assume that we want 2 scopes for the subnet.
You wil need to turn on DHCP on a second server in the network - preferably on a different subnet than the first, as this will help redundancy and as an alert mechanism.
To do this, we will need the network team to add the second DHCP server to the interface.
They should know how to do this.
anyway, so here is our template.
An example:
Scope #1 on DHCP server #1
172.16.23.x /24
.1 - .5 - router/switch static (exclude from scope)
.6 - .10 reserved (exclude from scope)
.11 - .20 printers (exclude from scope)
.21- .121 lease addresses
.122 - .254 reserved (exclude from scope)

Scope #2 on DHCP Server #2
172.16.23.x /24
.1 - .5 - router/switch static (exclude from scope)
.6 - .10 reserved (exclude from scope)
.11 - .20 printers (exclude from scope)
.21- .121 reserved (exclude from scope)
.122 - .254 lease addresses

when machines yelp for an address, typically the router sends to the DHCP servers and the server to respond first, gets the address.
placing the second scope in a remote data center for redundancy, almost ensures that the nearer server replies quickly.
after .21 through .121 in the example are provided addresses, .122 will be served from the second server.
this will occur until it hits .254

This will help in two ways.
1. DR - if the first DHCP ever tanks, a second server can jump right in.
2. Troubleshooting - if you see devices with IP addresses above .121 even though the first server has addresses available, something is interfering, slowing down, etc.

Another Tip - it is possible to deliver so much more than the simple IP address, gateway and DNS.
Check out all of the different options and you may find something of value you may have needed for a while.

Drop a note or find me on linked in if i can help some more.

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Reponse To Answer

by gautam.sanjog In reply to DHCP Scoping

hi can you guide me now to do in revised setup
In-short Issue of 192.168.100.1 to 192.168.100.254 Scope Range it's Assigned to pc + servers & some of static device. Now needs to Add some more PC in same network but DHCP server not able to give IP Due to All IP used .. what is solution

setup detail
DHCP server with server 2003 Operating System
Server IP - 192.168.100.8 ( it's with DHCP & DNS )
DHCP server Scope : 192.168.100.1 to 192.168.100.254
sub net Mask . 255.255.255.0
Default gateway 192.168.100.1 ( sonicwall router )
exude IP 192.168.100.1 to 192.168.100.70
sonic wall Router : 192.168.100.1

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setup

by gautam.sanjog In reply to DHCP Scope

hi can you guide me now to do in revised setup
In-short Issue of 192.168.100.1 to 192.168.100.254 Scope Range it's Assigned to pc + servers & some of static device. Now needs to Add some more PC in same network but DHCP server not able to give IP Due to All IP used .. what is solution

setup detail
DHCP server with server 2003 Operating System
Server IP - 192.168.100.8 ( it's with DHCP & DNS )
DHCP server Scope : 192.168.100.1 to 192.168.100.254
sub net Mask . 255.255.255.0
Default gateway 192.168.100.1 ( sonicwall router )
exude IP 192.168.100.1 to 192.168.100.70
sonic wall Router : 192.168.100.1

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Reponse To Answer

by Charles Bundy In reply to setup

OK -

First - I wouldn't follow will's advice on setting up multiple DHCP servers. You are on a single subnet, so that's just overkill.

Second - The above setup should be OK, but I would remove the exclusion and just set the address pool to 192.168.100.15 - 192.168.100.254. Then check the scope properties and make sure the lease duration is set to something like 3 to 10 days. Also make sure your router IP (192.168.100.1) is in the scope options along with DNS (192.168.100.8 + 'ISP') and TS (192.168.100. IP's.

Third - Make certain the sonicwall router DHCP service is turned off.

Hope this helps.

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Shorter Lease-Times, Second Subnet, or Mask Change

by tom.marsh In reply to DHCP Scope

As others have mentioned...

1) Shortening your lease time will free many IPs, as the DHCP server will consider addresses "in use" during most of the life of the lease, even if the device holding that lease hasn't been on the network in days or weeks. If your problem is mobile clients they should be on a separate subnet anyway, and can then also have their separate DHCP scope set very short... like 8-24 hours maximum.

2) You could split your network into a multiple subnets, but as others have mentioned, you'll need a Layer 3 device of one sort or another to route traffic between the subnets... If your existing equipment can handle it this is probably the best choice, even though it does represent a fair amount of administrative work. If it doesn't, this is still the best choice--budget for a new piece of gear to handle the situation and move forward.

3) Change the mask: This is the worst choice, and will make your network harder to support int he future if you see further growth that requires even more addresses. I would view this as a "stopgap" rather than a "solution." In the long run, option 2, (or some combination of option 1 and option 2) are still the best choices.

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adding vlan

by -nhone- In reply to DHCP Scope

adding vlan network to your setup may help you connect your other pc
and you can also add another dhcp scope by taging vlan id to it.

using class b ip address may give you more ip address

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