A Default Gateway in most cases is a router, which possibly knows where to route every packet, if it doesn't know where, it will drop the packet.

--->A situation where you might knowingly/unknowingly configure two default gateways:


Using a desktop PC with two NICs or a laptop with a Wireless NIC and a LAN, you try to configure a brand new network device or change already configured network device like a Access point, Switch, Router, Wireless Bridge etc at your work place or at home. You would be on your corp-network/Internet through your primary card i.e. say NIC1. You will connect the device to your laptop/PC using a cross-over cable if a router or a Straight-through cable if a switch to your second NIC, and then you put in IP, Netmask, Gateway info on this card, say NIC2. With this setup you will have network connectivity issues. This is due to fact that, your PC/laptop's routing table has two default routes with two different EXIT INTERFACES causing confusion as to which one to use to send packets. Below is routing table of one such example from a Windows PC.
Here Corp-network is 10.10.100.0 and the Network device is on 192.168.2.0 Subnet.

IPv4 Route Table
===========================================================
Active Routes:
Network Destination               Netmask          Gateway       Interface          Metric
          0.0.0.0                            0.0.0.0      192.168.2.1    192.168.2.104     30
          0.0.0.0                            0.0.0.0      10.10.100.1        10.10.100.5     30
        127.0.0.0                      255.0.0.0          On-link                127.0.0.1    306
        127.0.0.1           255.255.255.255         On-link                127.0.0.1    306
  127.255.255.255     255.255.255.255         On-link                127.0.0.1    306
      192.168.2.0             255.255.255.0         On-link        192.168.2.104    286
    192.168.2.104       255.255.255.255         On-link        192.168.2.104    286
    192.168.2.255       255.255.255.255         On-link        192.168.2.104    286
        224.0.0.0                       240.0.0.0         On-link                127.0.0.1    306
        224.0.0.0                       240.0.0.0         On-link        192.168.2.104    286
  255.255.255.255     255.255.255.255         On-link                127.0.0.1    306
  255.255.255.255     255.255.255.255         On-link        192.168.2.104    286
===========================================================

From the above table we can see that there are two default route entries and so the PC would be confused which interface to use as its exit interface.

Solution:
Solution to this is to leave out the Default Gateway entry blank on the NICs of the PC, like in this example: -------------------------->

With this setup you wouldn't have any network issues reaching your corp-net/internet. Per the example in picture PC now has only one route entry for 192.168.2.0 Sub-net whereas it had two entries before, one for 0.0.0.0 i.e. "any" and another for "192.168.2.0", Notice this as highlighted in the route table above. Now the your PC knows to only send packets destined for 192.168.2.0 Sub-net on NIC2.


If you want to be more granular and tell your PC exactly which NIC to use when sending packets with certain destination subnet, you can do so by manually adding a route entry like below.

C:> ROUTE ADD 192.168.X.0 MASK 255.255.255.0 192.168.X.1

Description: route ADD “network” MASK “subnet mask”  “gateway ip”
What this is saying is anything with destination IP in 192.168.X.0 subnet send it to gateway 192.168.X.1
 
With this setup you should have no issues reaching your Corp-Network/Internet as well as the 192.168.2.0 network simultaneously.

IP Cameras or Network Cameras have ethernet interface to deliver video and PTZ(Pan/Tilt/Zoom) control to a standard PC whereas DVRs i.e. Digital Video Recording require analog to digital capture cards in the PC to deliver video and PTZ control. In many ways IP Cameras with NVR software is a better surveillance system compared to DVRs. Main advantages are easy-installation and cost-effective. For more differences between DVRs and NVRs please check this page
This post is about NVR surveillance system, a comparison of performance and prices on few surveillance software that I tried. I used Axis 214 and Vivotek PZ6112 network cameras to test.

ZONEMINDER

• This is a free Linux-based open-source surveillance application.
• Installation is rather tedious and may require dealing with quite a good number of errors before you can really use it. But the good news is you can get it pre-installed on a  liveCD at zoneminder.com in the downloads page. or  a Virtual appliance which is a VMWare Virtual Machine based off of Ubuntu from Viktor Petersson. I tried Virtual appliance
• After downloading the Virtual appliance I had to use VMWare's Vcenter to convert .vmx file to .ovf and chose to upload the VM to my ESXi datastore.
• To open zoneminder application's home page where I can add/remove cameras, I opened a browser and typed in http://localhost/ or I could've typed in VM's IP address in any of the LAN machines like http://x.x.x.x
• I clicked on "add monitor" and added my two cameras but only saw black screen. After matching the screen resolution on zoneminder's camera settings to that on the camera itself which was 352 x 240 I saw the video.
• Axis was working fine but Vivotek PZ6112 is flapping. If I open vivotek camera settings on the zoneminders page and save it even without making any changes it comes back up but only for a while and then it goes black.
• All-in-all zoneminder was not ideal in my case, I did not like the user interface but you can't ask much for free.

Argus Surveillance
Next I tried argus surveillance. I tried this on windows 2003.

• Installation is pretty simple and adding in cameras was fairly easy. I don't have to point the exact path where the video is on the camera, just put in the IP address of the camera, authentication info and port no. which by default is 80. And it picked up both the cameras, very nice user interface, you can view and control all your cameras at one place. No flapping on the Vivotek PZ6112, however, the video is not as smooth as it is for Axis. The software did excellent on Axis only, but on PZ6112, the frames are jumping, sudden transitions, like when a person walks and then disappears. On the Axis its really like a video. 
• Load on CPU is not high and price for 8 channels/cameras is $118 which is good deal.
• Definitely worth trying if you have IP cameras other than PZ6112.
• Here is their website http://www.argussurveillance.com/

VisionGS
Finally, VisionGS worked for both the cameras Axis 214 and Vivotek PZ6112. Axis as with any other software worked without a problem but this software handled Vivotek PZ6112 as well. Video is very smooth, user interface is simple and neat, you can view and control all your cameras at one place like in seperate windows, nice motion detection. There is a huge list of supported cameras and the software is quite updated. Check out the features:

Short feature overview of VisionGS BE and VisionGS PE

• Real multi-cam support with own profiles.
• Live streaming video and audio using the latest streaming technology (e.g. WMV8 and WMV9).
• Support for a large number of video devices and webcams, dv/firewire included.
• Support for a large amount of network cameras (IP-Cams).
• Configurable motion detection to monitor your desk, house, children etc. (also ability to capture video in realtime).
• Most storage location (local harddisk, NFS, FTP, USB-Stick etc.)
• Ability to run as true Windows Service.
• Remote control your PTZ camera.
• Logitech Quickcam Orbit- and Logitech Quickcam Sphere Pan Motor control.
• Ability to include file-contents (e.g. latest weather information) in your webcam image.
• Include an overlay image like your company logo.
• Comes with configurable Java Applet for your website.
• Support for Dynamic DNS Service, e.g. DynDNS.com
• Archive images in chronological or reverse chronological order.
• Send live picture by Email to a friend.
• Multi language support (English, German).
• Comes with a configurable HTTP Server.
• HTTP password protection.
• IP Upload Feature to automatically update your website.
• Automatically creates thumbnails of your webcam pictures.
• Comes with lots of html examples.

Surprisingly price is quite low, its $29.95. It doesn't say how many cameras but from the comparison chart of Private Edition which is free with lots of limitations and Business Edition we can see "unlimited operation with network cameras." Check out the comparison of features below from their website.

Description / Feature	VisionGS Private Edition (PE)	VisionGS Business Edition (BE)
Unlimited live stream streaming.	-
Can run as true Windows NT service.	-
No VisionGS PE banner added randomly to the webcam image.	-
Unlimited operation with motion detection.	-
Access to the latest beta releases and information.	-
Unlimited operation with network cameras.	-
Access to commandline-parameter.	-

EyeSoft

• This is a bit expensive than others but you get a lot more than what you pay for. I would say this is excellent, user interface is absolutely fabulous, lots of features like storage indicator which would tell if you're running out of storage space, storage recycling which allows you to choose to delete old recorded video files etc. It was able to handle both the PZ6112 and Axis 214.
• Price for 8 cameras is $264. 
• Compared with other expensive surveillance software out there I would say the price is nothing for what this software offers.
• Installation and adding cameras is fairly simple, not at all a hardware resources hungry application. There are youtube videos on how to install and add cameras which should be more than enough to get you started. Check out the screenshot of main window HERE 
• Here is their website - http://www.bikal.co.uk/network-surveillance/ip-software.html

To Sum up:
There are quite expensive surveillance software out there like Milestone XProtect, GeoVision, VideoInsight, BrickHouse Security etc. I haven't tried these just because they're way expensive, costing atleast $500 for only 4-channels. If you're budget is under $300, you may decide one among the four I tested. Although PZ6112 is the only model I had trouble with in Zoneminder and Argus Surveillance I am sure they'd cover most IP Cameras.

• If Argus Surveillance would've supported Vivotek PZ6112, I would've gone with that and pay $118 for 8 cameras.
• If I am running low on budget and prefer something free then Zoneminder is the option. 
• If I want some nice user interface, control, simple installation and configuring I'd go with VisionGS for $29.95
• If I want something real even if I had to spend $264 for 8-channels then Eyesoft is the way to go.