You may be thinking "but mDNSResponder is the multicast dns responder." You're right that's what it originally was for, and it still fulfills this function. The system DNS resolver on Lion is the mDNSResponder process. I've not upgraded so I am not sure of the discoveryd behavior w/r/t DNS lookups and /etc/hosts. Update: OSX 10.10 Yosemite has replaced mDNSResponder with "discoveryd". Update(2): OSX 10.10.5 brings the return of mDNSResponder. This allows you to have the whole *.dev namespace for development (for instance), without having to individually enter every domain you want resolved locally into /etc/hosts One advantage of running something like dnsmasq locally (besides the significant performance boost) is that you can redirect whole top-level domains back to your local machine. There is a considerable disk/CPU hit from having to read /etc/hosts on every request, so it is in your best interest to keep that file very light.
![best photo editor for mac os x lion best photo editor for mac os x lion](https://www.popsci.com/uploads/2019/03/18/DHYU4XU23LBIEVQ542GN2FRLV4.png)
On a related note, if you make heavy use of the hosts file (for adblocking, local web development, etc), you may want to look into running your own local DNS resolver. Interestingly, if you happen to have a local webserver running on 127.0.0.1:80 and your browser receives a response from the webserver (error or otherwise), no AAAA query is issued, as it seems to be satisfied that a TCP connection was at least possible.
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The ad servers indeed have IPv6 addesses and were able to serve me their content. I fired up wireshark and noticed AAAA (IPv6 DNS records) queries following the IPv4 A queries (IPv4).
![best photo editor for mac os x lion best photo editor for mac os x lion](https://static.listoffreeware.com/wp-content/uploads/image-tricks-lite-fs-2016-03-29.png)
I discovered this when I noticed some ads that I had never seen before on Snow Leopard because I had redirected the ad domains to 127.0.0.1. With regards to overriding domains in the hosts file, I have found that in some circumstances, Lion queries the IPv6 address for a domain if it senses that a domain is unreachable over the IPv4 network.