Solved

Help with dual NIC config?

Posted on 2013-10-30
10
277 Views
Last Modified: 2013-11-22
Hi,

I was hoping someone could expain this dual nic config that one of our customer's has.  The first nic is public (and appears to have a nat'd ip) while the second is private (with non-nat'd ip).  Everything is currently working, but I'm curious as to 1) why there is no gateway defined for the public IP?  2) why a nat'd IP for the public? and 3) what is the significance of the default route?  Below is the ipconfig snippet (with the ips changed of course)  along with the default route:

Ethernet adapter Public - 1.2.3.4:

   Connection-specific DNS Suffix  . : users.public
   IPv4 Address. . . . . . . . . . . : 1.2.3.4
   Subnet Mask . . . . . . . . . . . : 255.255.254.0
   Default Gateway . . . . . . . . . :

Ethernet adapter Local Area Connection 4:

   Connection-specific DNS Suffix  . :
   IPv4 Address. . . . . . . . . . . : 5.6.7.8
   Subnet Mask . . . . . . . . . . . : 255.255.252.0
   Default Gateway . . . . . . . . . : 5.6.7.89
-----------------------------------------------------
 IP               MASK        GATE          METRIC
0.0.0.0          0.0.0.0     5.6.7.89       1  

Thanks!
0
Comment
Question by:blinkme323
  • 3
  • 3
  • 2
  • +1
10 Comments
 
LVL 6

Assisted Solution

by:ButlerTechnology
ButlerTechnology earned 250 total points
ID: 39612765
A system with multiple NICs will tend to only have a single IP address that has a default gateway.  In a simple NAT network, the IP without the gateway address will be the gateway for the clients on the internal network.  The purpose of the default gateway is to allow the system to access outside resources -- specifically the internet.  The route is the catch all.  If there isn't a matching route than the default gateway is used.

Tom
0
 
LVL 83

Accepted Solution

by:
Dave Baldwin earned 250 total points
ID: 39612824
Yes, that's the way I have mine setup and for the same reasons as Tom listed.
0
 

Author Comment

by:blinkme323
ID: 39613088
Thanks for the follow up.  That's why I can't get my head around this one since the private nic seems to have the gateway.
0
 
LVL 83

Expert Comment

by:Dave Baldwin
ID: 39613126
That would be Ok if somewhere on that network is a router that goes out to the internet.  That would leave the 'Public' IP for traffic to the server instead of local traffic that goes out to the internet.
0
 
LVL 6

Expert Comment

by:ButlerTechnology
ID: 39613782
Just for clarification...

Ethernet adapter Local Area Connection 4:

   Connection-specific DNS Suffix  . :
   IPv4 Address. . . . . . . . . . . : 5.6.7.8
   Subnet Mask . . . . . . . . . . . : 255.255.252.0
   Default Gateway . . . . . . . . . : 5.6.7.89

Is this the NIC that is connected to your ISP?

Tom
0
Network it in WD Red

There's an industry-leading WD Red drive for every compatible NAS system to help fulfill your data storage needs. With drives up to 8TB, WD Red offers a wide array of solutions for customers looking to build the biggest, best-performing NAS storage solution.  

 

Author Comment

by:blinkme323
ID: 39613883
No, that is private connection for internal routing (server to server, content switch, etc).
0
 
LVL 6

Expert Comment

by:ButlerTechnology
ID: 39614003
This might sound silly - Can you unplugged the cable to your ISP to verify that it is the correct NIC in the system?

Tom
0
 

Author Comment

by:blinkme323
ID: 39614220
Unfortunately, I can't disconnect at this time.
0
 
LVL 23

Expert Comment

by:masnrock
ID: 39617510
No need to disconnect anything, just trace the cables and make sure that things are going to the right place. I'm assuming that the client's network is working properly in spite of its quirks? I'd be wondering if the NIC with the public IP address is even in use for anything. If this is the server we're talking about, maybe it had previously been used as a router?
0
 
LVL 23

Expert Comment

by:masnrock
ID: 39617913
Better yet, is there a private network making use of public IP addresses? Doesn't make sense, but it wouldn't be impossible either.
0

Featured Post

Microsoft Certification Exam 74-409

Veeam® is happy to provide the Microsoft community with a study guide prepared by MVP and MCT, Orin Thomas. This guide will take you through each of the exam objectives, helping you to prepare for and pass the examination.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Meet the world's only “Transparent Cloud™” from Superb Internet Corporation. Now, you can experience firsthand a cloud platform that consistently outperforms Amazon Web Services (AWS), IBM’s Softlayer, and Microsoft’s Azure when it comes to CPU and …
A procedure for exporting installed hotfix details of remote computers using powershell
This tutorial will walk an individual through the process of transferring the five major, necessary Active Directory Roles, commonly referred to as the FSMO roles to another domain controller. Log onto the new domain controller with a user account t…
In this tutorial you'll learn about bandwidth monitoring with flows and packet sniffing with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're interested in additional methods for monitoring bandwidt…

930 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

18 Experts available now in Live!

Get 1:1 Help Now