Performance, which is better: NAT vs Bridged Network

[jnl2]

Host: Win 7
Guest: VBox v 4.3.20 w/ Additions - Win 7

Both the host and the guest are afforded roughly the same memory resources: 4GB of RAM and 100GB of HD.

I'm relatively new to networking concepts but I have a low level grasp of the differences in terms of how the guest's traffic is packaged within the overall IP traffic of a computer when NAT is used and how a Bridged Network is assigned its own IP address by the firewall/network adapter. So my question is, and it may not be a relevant one, if one is running only one guest, is there performance benefits to using one network setting or the other for mundane internet activities?

Thanks!!

[mpack]

I merged your (nearly identical) security and performance questions into one.

Both are better - when the right situation comes along.

NAT means that the VM uses the hosts internet, just like any other host app would. Basically, if the host has working internet then so will the guest. The downside is that outside of your PC, there's no way to tell that there are really two PCs there, which makes it difficult (unless you're an expert) for the VM to have an independant network life, e.g. to work as a server of something.

Bridged means that the VM shares the hosts's network card. When transmitting it spoofs a different MAC address for the VM. To the outside world it looks like two (or more) PCs on a switch. In particular a router will see two separate MACs and assign IP addresses to each of them, and route incoming packets equally to each of then. The VM has full participation on the network - at the cost of requiring an external network that's capable of accomodating them, e.g. an external router.

Performance is not a factor. That's dictated by the network.
Security? I've heard people assert either one is more secure. I personally don't see much difference. Security holes come from exchanging executable files between PCs, not from the mechanism used for an internet connection.

[jnl2]

Thanks for the reply.

I broke my last query into two posts after another user suggested doing so in another unrelated thread when posting questions on this board. Maybe doing so made it easier for future users to search for information on topics.

In any case...

With the performance question, (and again bare in mind that I am not knowledgeable with regards to networking besides basic plug and play approaches) I was thinking in terms of a NAT connected guest somehow competing for resources (RAM and HD) with the host.

Then, with the security question, my concern sprung from a similar concern. This being that security threats could co-mingle between the host and guest since the two memory devices could be utilized when emulating a router in a NAT configuration.

At least schematically to me, in a Bridged Network configuration less RAM/HD resources are used to handle the guest's requests. As for whether or not a NAT adds or detracts vulnerabilities between the host and guest, I do not know.

Sorry for this newbie's approach to networking.