• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 1199
  • Last Modified:

DHCP client with no internet access

I set up DHCP Server 2003 on 2 NICs and the clients do get an ip assigned. But they don't have internet access.
The set up:
 Server NIC1 ( external)
ip 192.168.1.55
sm 255.255.255.0
dg 192.168.1.254
dns 192.168.1.254

Server NIC2 (internal)
ip 192.168.1.56
sm 255.255.255.0
dg 192.168.1.55 the point to the
dns 192.168.1.55

On the client pc:
Obtain an IP address automatically
Obtain DNS server address automatically
PS> I've researched the net and most offer guides as to how to set up a DHCP server but not how to test.
Thank you
0
mechanicus01
Asked:
mechanicus01
  • 11
  • 8
  • 2
  • +1
2 Solutions
 
Donald StewartNetwork AdministratorCommented:
If DHCP is used to assign IP addresses on the LAN, the DHCP server should be configured to not provide a default gateway.  


http://www.topwebhosts.org/articles/setup-multihomed-host.php
0
 
Jakob DigranesSenior ConsultantCommented:
here i'd do some route testing.
Open CMD:

ping default gateway on client
ping IP of LAN Nic on server
ping IP of EXternal NIC on server
ping DNS-server
ping default gateway on External NIC
ping a public IP (Ex: 195.88.55.16)
ping a public webpage (ex: www.bbc.co.uk)

This will show you where connection ends.
You could also try tracerouting a packet;
open CMD
tracert www.bbc.co.uk
tracert 196.88.55.16


0
 
Jakob DigranesSenior ConsultantCommented:
that gives you a start to standard troubleshooting internet connection
0
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
mechanicus01Author Commented:
Ok, i followed both you guys instructions and when i do a ping from the client pc i can successfuly get responses back from all except from external IPs or external websites.
ie when i ping google.com i get : ping request could not find host google.com
0
 
Jakob DigranesSenior ConsultantCommented:
and you got no response from 196.55.88.16 IP ??
Have you set up Routing and remote access on the server?
0
 
Jakob DigranesSenior ConsultantCommented:
the request could not find host error means you get no result from DNS or DNS is unreachable.
I see you have only internal DNS. Have you set up forwarding correct?
0
 
mechanicus01Author Commented:
im testing some more. Do you have a guide for setting up forwarding DNS records?
0
 
Jakob DigranesSenior ConsultantCommented:
http://www.petri.co.il/configure_dns_forwarding.htm it's for WIn2000 but should like more or less the same as WIn2003.

Forward all requests to ISPs DNS
(you could also try putting ISPs DNS as second DNS handed out by DHCP - for testing purposes only)
0
 
mechanicus01Author Commented:
On server 2003 do i set static ips to both NICs? but without setting a default gateway on the internal NIc?
The server is set up as DNS, and DHCP.
 Server NIC1 ( external)
ip 192.168.1.140
sm 255.255.255.0
dg 192.168.1.254
dns 192.168.1.254

Server NIC2 (internal)
ip 192.168.1.56
sm 255.255.255.0
dg 0.0.0.0
dns 192.168.1.140

Is that right?
and the clients just let DHCP assign Ips?
0
 
Jakob DigranesSenior ConsultantCommented:
Do you have routing and remote access configured on the server?
And why do you have two NICs connected to the same LAN, this is not necessary.
But if you have two NICs connected to different LANs it would be okay, but then you would need Routing and Remote access set up for IP-routing (nothing more)
And then you should remove gateway and use static routes in routing and remote access (RRAS)
Try disabling one of the NICs and use only one with Gateway 192.168.1.254 and either same GW on clients or serverIP as gatewaym but then the server HAS to be a RRAS server.

Gateway = Where a computer sends packets that is not destined for LAN, but internet. The gateway then has to know where to send the packet to get it tot the internet, i.e. which router would be the next one
0
 
mechanicus01Author Commented:
Ok, i tried that and i still get the same results.( i can ping everything else except the outside world)
So, i made this drawing with the parameters as of now:
Please let me know where i am making the mistake
mynet.png
0
 
Jakob DigranesSenior ConsultantCommented:
try the following:
create a static route like this:
Interface (NORTH)
destination: 0.0.0.0
mask: 0.0.0.0
gateway: 192.168.1.76

This is because the routes for 192.168.0.0 and 192.168.1.0 networks are reachable through the fact that they are connected. You need to tell the server where to send traffic that is not destined for LAN, i.e. all other traffic (0.0.0.0/0.0.0.0)

Can the server browse the internet?
0
 
mechanicus01Author Commented:
i addded this static route
Interface (NORTH)
destination: 0.0.0.0
mask: 0.0.0.0
gateway: 192.168.1.76

Afterwards, i can not browse the internet.
0
 
Jakob DigranesSenior ConsultantCommented:
assuming you're on the 192.168.0.x network. Can you ping 192.168.1.76 ?
try changing interface to SOUTH and gateway to 0.1
0
 
ChiefITCommented:
Why the interest in Multihoming the entire domain? Multihomed computers have problems with the ARP table as well as DNS, DHCP and Netbios translation.

Why not use one nic for all computers/servers and then add them to a switch?

RRAS on the server effectively makes it a router. You also have the subnet mask on the server as 255.255.255.255, meaning it is its own broadcast domain. The router is providing DHCP and therefore DNS, this means it will not store the DNS SRV records and you will end up with authentication as well as replication issues if you put in a replication partner.

Let the router do the routing for you. Let the switches to inter LAN communications.

On the switches there is a thing called spanning tree protocol that prevents L2 loops on an L2 network. That means your switches will prevent traffic on one of these two nics, by default.

On each computer with dual nics, you are looking at a messed up routing table.


RRAS will, by default, enable Windows Firewall, and block AD traffic.

Let me understand the implications of dual nics and I think we can work out the fine details. It will take a lot of work. Just let me know of your intentions.
0
 
mechanicus01Author Commented:
Ok, i am willing to let go of the idea of 2NIC server. What i am trying to do here i set up a DHCP, get it working and then proceed to install ISA server 2006.

I tried installing the DHCP server after i had the ISA installed and it was a mess- i couldn't get it to work.

The objective here is to get the DHCP working first as it will simplify the configuration of the ISA 2006 Server afterwards.

* Dont i need 2 NICs for a DHCP server? one to accept internet traffic and the other to relay traffic to/from the LAN to the internet? Do you have a diagram of how DHCP server topology should look like?
0
 
Jakob DigranesSenior ConsultantCommented:
is this as SBS server?
if so - do not use the ISA on it :-)

Assuming you already have a router on yout network, you can disble one NIC on your server and just have it as DHCP
Why do you want to install ISA on that server?
A DHCP server only hands out addresses to clients, and can either point to external gateway or servers gateway as long as this one acts as a router
0
 
Jakob DigranesSenior ConsultantCommented:
ah --- didn't see the 255.255.255.255 subnetmask :-S
0
 
mechanicus01Author Commented:
i have exchange and sharepoint services that i want to hide behind ISA 2006 and then publish them thru ISA.
Let me test the 1 NIC scenario and see how that works.

It is a Win 2003 R2 Enterprise
0
 
Jakob DigranesSenior ConsultantCommented:
Ok --- how many servers do you have?
Or have you put all on a single server?
It's possible to all those things on a server with 1 NIC as long as you have at least one router that can give you internet access
0
 
ChiefITCommented:
I believe what you are trying to do is use a DHCP relay agent. This will provide DHCP to your VPN clients that VPN into your network??

Please advise what you need DHCP for outside the LAN, or should I say outside the broadcast domain?
0
 
mechanicus01Author Commented:
I might have worded the question incorrectly as it is a subject i am not too familiar with and because there are  some things unknown to me
0

Featured Post

Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

  • 11
  • 8
  • 2
  • +1
Tackle projects and never again get stuck behind a technical roadblock.
Join Now