Will changing HOSTS file to block unwanted sites mess up IIS?

I've got IIS set up on 127.0.0.l and I'm tinkering with adware blockers that u开发者_JS百科se 127.0.0.1 as the address to route malicious sites to (127.0.0.1 www.badsite.com)

Will this make all calls to those sites hit my IIS and make it load a default page?

Is there a way to still block these sites via HOSTS without hitting IIS?

On Win 7 pro.

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Yes, all calls to those sites will hit your IIS instance. IIS might return a default page, or a "file not found" page, or if it has an actual page it might return that.

127.0.0.1 is used because it always points to the local machine, which prevents your computer from wasting bandwidth (and possibly DDOSing some poor victim) by trying to send these packets externally. You could try 127.0.0.2 or 127.254.254.254, which would work IIS is listening on 127.0.0.1 specifically or 127.0.0.0/24 rather than on every address on the loopback interface.

There isn't any other address guaranteed to not reach the public Internet, although you may be able to set one up yourself by locally blocking outgoing packets to 192.0.2.1 or the like in your firewall.

Other options for ad blocking include using a local proxy which would return HTTP 404 or the like for blocked URLs or a local DNS relay that would return NXDOMAIN for blocked domains.

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Yes, as Anomie points out, they will hit your IIS and then will serve the default page or an error status or an actual page if it finds one (unlikely however).

To avoid that, I use 0.0.0.0 as the address. I've been using it with MVPS Hosts file without any issues for years now.

Also, as this post suggests, you can use 0 too (any invalid ip will do I guess)

Both of these will be a bit faster as they will avoid the wait for timeout on 127.0.0.1.

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Another option would be to run IIS another port. If you are running behind a firewall or something like a home router, you could set it to port forward port 80 for incoming requests to your alternate port. (If you're using IIS inside, you'd need to go to http://[your ip address]:[alt port])