My PC has two connections (wireless and wired) simultaneously. Both of them have an internet connection.

In this situation, how does it connect to the internet? How do my LAN and WLAN interfaces know to send requests to the web?

  • 1
    Are you asking which connection is being used? Which operating system are you using? Feb 15 '12 at 3:19
  • Connected both of them. Yes!
    – KevinOelen
    Feb 15 '12 at 3:21

If multiple interfaces are up there are two issues. First one is which interface has gateway and what is the interface order.

I'm assuming you're using Windows O.S. In command prompt (type "cmd" in Run window) type route print and you should see something like this:


(the headers are in you o.s. language, mine is Turkish)

Which interface has the gateway option, actually which interface has the routing information for destination, mask is the actual outgoing door...

{ Edit: Observe that I have a route line that is

Destination: Mask: and Gateway

at the bottom. That says when i need to access network, i have to pass throug the 24.2 gateway. Besides, there are no entries in main table for network, that was an experimental entry over another NIC }

When you have multiple route informations for that destination {edit:} and each one is different from each other or just two different gateways, you're doomed. Network will start losing some packets...

When you have multiple route informations for that destination but one gateway for each (which is your case that your gateway will be your modem i guess, which is your dhcp server, it'll assing different ip addresses for each interface but same information for default dns and default gateway) then there is an order:


Your o.s. will treat your up and running interfaces with this ordering. So if you wireless interface is on the first line and connected, your o.s. will use that interface for network communication and vice-versa.

  • 8
    That second screenshot is of the Adapters and Bindings window, which can be brought up in Windows 7. Go to the Network Connections window, press ALT once to bring up the menu bar, go to Advanced > Advanced Settings....
    – Bob
    Feb 15 '12 at 4:53

I was wondering this myself when I installed a wireless NIC in my system. I did some test (in Windows XP) and found out that if you have both a wired and wireless connection (both independently configured and functioning), then Windows will prioritize the wired connection.

In other words, when the cable is disconnected, it will use the wireless connection, but when you plug in the network cable, the wireless connection is essentially stopped (not disabled, just no longer used, that is, zero bytes transfered in either direction) and the wired connection is used instead.

When my mother got a laptop, I repeated the test with it (in Windows 7) and got the same results.

For the record, this behavior makes sense. A wired connection will be faster and more secure than a wireless one. Why use the wireless one if the wired one works?

How does[sic] my Lan and Wlan interfaces know to send request to web?

The network adapters do not decide that, the operating system does. Windows decides which interface to send and receive from.

(I could not test it, but I do not believe that the choice of which adapter to use depends on the speed. I suppose it could use a faster wireless connection over a slower wired one, but that would be a bizarre setup indeed. Also, note that I am talking about a wired vs. wireless connection as per the question, I am not discussing multiple wired connections and redundancy. In the case that the prioritized wried connection goes down, obviously Windows switches over to the wireless one.)

  • There's probably some other method since i use a gig-e wired connection between two systems (non internet) and wireless internet. Its not speed related.
    – Journeyman Geek
    Feb 15 '12 at 5:42
  • No, I wouldn’t imagine so. I suspect that it first prioritizes wired connections over wireless ones, and then in those two sub-groups, it uses the order that The_aLiEn described.
    – Synetech
    Feb 15 '12 at 5:46

Sorry if you already found the answer, but this is possible and is really nice.

Cisco routers are able to make two connections to one device, depending on the types of connections it's either unequal cost path load balancing, or equal cost path load balancing. The router will transfer the data through both connections, it'll increase file transfers, maybe downloads depending on your connection to the modem, what your plan with the ISP is, but it should increase your download speed, most slow connections are a result of the wireless connection. You usually find this being used with servers, or NAS devices, usually where multiple users or other devices are sending/receiving data from the storage devices. If it's set up properly, it will make a noticeable difference. If you want maximum speed for a laptop, you're best bet is getting a Cisco Gigabit router with wireless-N, or wireless-AC, unless you're using a desktop, then two cat6 connections would be... just.... wow. Hope this helps


It is unlikely that both interfaces are simultaneously active. When one interface is active, the other(s) are inactive. Windows will send traffic through the default active connection. Your machine will, unless you've done some deliberate configuration, use only one interface at a time.

That said, you can have two interfaces active in a computer, but they will have to be on different subnets to function successfully. The internet-facing interface will send non-local packets out to the public network; the LAN-facing interface will send packets locally on the local area network. This is how routers work: they examine packets and determine based on IP address which interface to send packets out of.


This is an old question, but in case it comes up in a search for answers:

On Windows operating systems, there is a setting for the interface 'metric', which defaults to 'Automatic metric'. This setting is accessed by clicking the Advanced button at the bottom of the main tab of the TCP/IP properties of the adapter. The metric is assigned by the operating system based on a determination of the cost of routing over that interface, and it normally should assign the lowest metric to the fastest-best connection, and use that connection when it is available.

In some cases you may wish to manually assign a metric; for example, I have both a LAN wired connection and a wireless connection, and both have Internet access, but they are both ultimately connecting through the same ADSL modem. My LAN connection is to another Windows machine, on which I have the LAN adapter enabled as a gateway for Internet Connection Sharing, and I can use that when I have my wireless disconnected or disabled, but when my machine's wireless is functioning, I want it to take precedence, because that other machine is using wireless itself for its connection to the ADSL modem. I do not have a wired connection directly to the modem at all. Windows, left to its own devices, would always use the wired connection to the other machine, but since I don't want that, I manually assigned both interfaces' metrics on my machine, and gave the wireless interface a lower metric, so it gets used when it is in service.

Reference: https://support.microsoft.com/en-us/kb/299540


Forwarding traffic is routed to low metric value interface, this is basic routing mechanism to if multiple gateways available and default behavior however with advent of software developments there are cases wireless connection is preferred. Another consideration is reverse traffic can be either of wired or wireless, since metric value is local to Windows hosts only, if your environment supports to keep wired active while wireless connected BIOS (at least Dell has this choice) level setting allows to automatically shutdown wireless when wired connection is active. This also reduces DHCP packets and keeps your DHCP server hygiene considering thousands of ip hosts.Helps DNS server with records updates and reduces wireless traffic

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