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Name resolution problems ever since cisco router install
I have had internal and external name resolution problems ever since deploying 2 cisco routers (2501s) in my LAN consisting mostly of windows boxes.. Schematic here: http://mvpbaseball.cc/network.jpg
All my hosts (on the 192.168.1.0 network and 192.168.2.0 network) can ping each other fine. They can also ping any WAN address fine (so long as you use the IP, not the host name of the WAN address). All my hosts can ping my gateway fine as well (cable router).
However, when it comes to pinging my ISP's DNS server.....none of my hosts can ping it. You are only able to ping my ISP's DNS server if you are connected directly to my cable router.
Any idea as to why local name resolution is not occuring? I know netbios broadcasts to resolve host names locally. Why isnt it working? I know routers dont forward broadcasts by default, but that shouldnt make a different for the hosts all on the same subnet?
Thanks
All my hosts (on the 192.168.1.0 network and 192.168.2.0 network) can ping each other fine. They can also ping any WAN address fine (so long as you use the IP, not the host name of the WAN address). All my hosts can ping my gateway fine as well (cable router).
However, when it comes to pinging my ISP's DNS server.....none of my hosts can ping it. You are only able to ping my ISP's DNS server if you are connected directly to my cable router.
Any idea as to why local name resolution is not occuring? I know netbios broadcasts to resolve host names locally. Why isnt it working? I know routers dont forward broadcasts by default, but that shouldnt make a different for the hosts all on the same subnet?
Thanks
ASKER
Sorry here is the address of the schematic
http://mvpbaseball.cc/post.jpg
I will get the route print to you soon, as I am at work.
My ISPs dns server is 68.34.76.5
My internal dns server is 192.168.1.98
I have all my hosts using either the 2501a cisco router as their gateway. Or the 2501b router as their gateway. When the clients plug directly into the cable router, everything works fine.
http://mvpbaseball.cc/post.jpg
I will get the route print to you soon, as I am at work.
My ISPs dns server is 68.34.76.5
My internal dns server is 192.168.1.98
I have all my hosts using either the 2501a cisco router as their gateway. Or the 2501b router as their gateway. When the clients plug directly into the cable router, everything works fine.
I will be able to troubleshoot a bit more when I see the "ipconfig /all" and "route print" output... It might actually be helpful to get that output from a client machine on each subnet, 192.168.1. and 192.168.2.
However, based on your network diagram, I have some concerns right off the bat:
1 - Why so many routers? A single Cisco router can easily act as a gateway between a WAN (internet) link and 2 or more private networks.
2 - Why include a DSL / Cable router in this situation? Those are intended for home users who do not have a more expensive, complicated solution (like your Cisco 2500s) available. I can't say this for certain yet, but I think part of your problem may be due to the fact that the cable router is not managable beyond a certain degree... ie, it has no idea that 192.168.0.* and 192.168.2.* are valid networks on its INTERNAL ports. Traffic bound for those addresses in some situations may be send back out through its default interface (the port connected to your cable modem and ISP).
However, based on your network diagram, I have some concerns right off the bat:
1 - Why so many routers? A single Cisco router can easily act as a gateway between a WAN (internet) link and 2 or more private networks.
2 - Why include a DSL / Cable router in this situation? Those are intended for home users who do not have a more expensive, complicated solution (like your Cisco 2500s) available. I can't say this for certain yet, but I think part of your problem may be due to the fact that the cable router is not managable beyond a certain degree... ie, it has no idea that 192.168.0.* and 192.168.2.* are valid networks on its INTERNAL ports. Traffic bound for those addresses in some situations may be send back out through its default interface (the port connected to your cable modem and ISP).
ASKER
This is my home LAN, just testing things out trying to learn Cisco.
I have a static route placed in my cable router, so it knows how to find the 192.168.2.0 network. When this wasnt in there, the 192.168.2.0 network couldnt ping WAN
I just added an internal DNS server and DHCP server (192.168.1.98). It's gateway is 192.168.1.1 and it CAN ping the WAN. All of my clients can now resolve names locally and remotely. However, I still cannot ping my ISP's DNS server (68.34.76.5) when I use the ciscos as the gateway. Pinging everything else on the WAN works.
Here is ipconfig all of the 192.168.1.0 client:
Windows IP Configuration
Host Name . . . . . . . . . . . . : dissolved
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Local Area Connection 4:
Connection-specific DNS Suffix . : 192.168.1.98
Description . . . . . . . . . . . : 3Com EtherLink XL 10/100 PCI For Complete PC Management NIC (3C905C-TX)
Physical Address. . . . . . . . . : 00-04-75-86-10-B3
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 192.168.1.5
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.40
DHCP Server . . . . . . . . . . . : 192.168.1.98
DNS Servers . . . . . . . . . . . : 192.168.1.98
Lease Obtained. . . . . . . . . . : Wednesday, August 11, 2004 4:54:05 PM
Lease Expires . . . . . . . . . . : Monday, May 07, 2007 4:54:05 PM
Here is the route
==========================
Interface List
0x1 ..........................
0x2 ...00 04 75 86 10 b3 ...... 3Com EtherLink XL 10/100 PCI For Complete PC Management NIC (3C905C-TX) - Packet Scheduler Miniport
==========================
==========================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 192.168.1.40 192.168.1.5 20
63.208.194.17 255.255.255.255 192.168.1.1 192.168.1.5 1
64.156.132.140 255.255.255.255 192.168.1.1 192.168.1.5 1
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
192.168.1.0 255.255.255.0 192.168.1.5 192.168.1.5 20
192.168.1.5 255.255.255.255 127.0.0.1 127.0.0.1 20
192.168.1.255 255.255.255.255 192.168.1.5 192.168.1.5 20
209.66.98.92 255.255.255.255 192.168.1.1 192.168.1.5 1
216.109.118.66 255.255.255.255 192.168.1.1 192.168.1.5 1
216.109.127.16 255.255.255.255 192.168.1.1 192.168.1.5 1
224.0.0.0 240.0.0.0 192.168.1.5 192.168.1.5 20
255.255.255.255 255.255.255.255 192.168.1.5 192.168.1.5 1
Default Gateway: 192.168.1.40
==========================
Persistent Routes:
None
I have a static route placed in my cable router, so it knows how to find the 192.168.2.0 network. When this wasnt in there, the 192.168.2.0 network couldnt ping WAN
I just added an internal DNS server and DHCP server (192.168.1.98). It's gateway is 192.168.1.1 and it CAN ping the WAN. All of my clients can now resolve names locally and remotely. However, I still cannot ping my ISP's DNS server (68.34.76.5) when I use the ciscos as the gateway. Pinging everything else on the WAN works.
Here is ipconfig all of the 192.168.1.0 client:
Windows IP Configuration
Host Name . . . . . . . . . . . . : dissolved
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Local Area Connection 4:
Connection-specific DNS Suffix . : 192.168.1.98
Description . . . . . . . . . . . : 3Com EtherLink XL 10/100 PCI For Complete PC Management NIC (3C905C-TX)
Physical Address. . . . . . . . . : 00-04-75-86-10-B3
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 192.168.1.5
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.40
DHCP Server . . . . . . . . . . . : 192.168.1.98
DNS Servers . . . . . . . . . . . : 192.168.1.98
Lease Obtained. . . . . . . . . . : Wednesday, August 11, 2004 4:54:05 PM
Lease Expires . . . . . . . . . . : Monday, May 07, 2007 4:54:05 PM
Here is the route
==========================
Interface List
0x1 ..........................
0x2 ...00 04 75 86 10 b3 ...... 3Com EtherLink XL 10/100 PCI For Complete PC Management NIC (3C905C-TX) - Packet Scheduler Miniport
==========================
==========================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 192.168.1.40 192.168.1.5 20
63.208.194.17 255.255.255.255 192.168.1.1 192.168.1.5 1
64.156.132.140 255.255.255.255 192.168.1.1 192.168.1.5 1
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
192.168.1.0 255.255.255.0 192.168.1.5 192.168.1.5 20
192.168.1.5 255.255.255.255 127.0.0.1 127.0.0.1 20
192.168.1.255 255.255.255.255 192.168.1.5 192.168.1.5 20
209.66.98.92 255.255.255.255 192.168.1.1 192.168.1.5 1
216.109.118.66 255.255.255.255 192.168.1.1 192.168.1.5 1
216.109.127.16 255.255.255.255 192.168.1.1 192.168.1.5 1
224.0.0.0 240.0.0.0 192.168.1.5 192.168.1.5 20
255.255.255.255 255.255.255.255 192.168.1.5 192.168.1.5 1
Default Gateway: 192.168.1.40
==========================
Persistent Routes:
None
Hmm, your cable router must have a lot more configuration options than mine, since you were able to add that static route for 192.168.2.0 :) That's a good thing in this situation, though.
With that in mind, your clients on the 192.168.1. subnet should be using 192.168.1.1 as their default gateway, and the cable router will know that any traffic bound for 192.168.2.* will need to go through the 192.168.1.40 router. That's a small design change, really. You'll notice how your local routing table has several entries for public Internet IPs, and the gateway listed for those IPs is 192.168.1.1 - this happens because the OS / IP drivers are smart enough to figure out at some point that 192.168.1.40 is not the router that should be handling those packets, and it dynamically adjusts your local routing table so future traffic to those IPs will take the most efficient route.
I don't know a great deal about how these communication protocols work, just the concepts and the result.
I am a bit stumped as to why you can't ping the provider's DNS server though, when all you changed was the gateway of your clients. Your name resolution is probably working correctly only due to the fact that your Server is configured with the 192.168.1.1 gateway, and all forwarded DNS queries pass through the server (not directly from the client workstations).
With that in mind, your clients on the 192.168.1. subnet should be using 192.168.1.1 as their default gateway, and the cable router will know that any traffic bound for 192.168.2.* will need to go through the 192.168.1.40 router. That's a small design change, really. You'll notice how your local routing table has several entries for public Internet IPs, and the gateway listed for those IPs is 192.168.1.1 - this happens because the OS / IP drivers are smart enough to figure out at some point that 192.168.1.40 is not the router that should be handling those packets, and it dynamically adjusts your local routing table so future traffic to those IPs will take the most efficient route.
I don't know a great deal about how these communication protocols work, just the concepts and the result.
I am a bit stumped as to why you can't ping the provider's DNS server though, when all you changed was the gateway of your clients. Your name resolution is probably working correctly only due to the fact that your Server is configured with the 192.168.1.1 gateway, and all forwarded DNS queries pass through the server (not directly from the client workstations).
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ASKER
Found the problem. Router issue.
Thanks man!
Thanks man!
Please post the output of "ipconfig /all" and "route print" from a PC that is having these problems. Also post the IP address(es) of your ISP's DNS server and your local DNS server (I assume this IP will be in your network.jpg once the link is fixed).