Franc Zabkar wrote:

And even more - any host that you access frequently you can
"hard-code" it's IP address in your hosts file - giving you
ultra-fast DNS lookups.

Excuse my ignorance, but wouldn't this slow down your browser?

No, because (as I explained in my previous post) the hosts file appears
to be cached in memory, making for very fast access.

I would argue that even if the system had to read in the entire hosts
file each and every time a DNS request was performed, that reading a 1
mb file on a typical system today is faster than performing a DNS
query. (it helps that file-caching would play a role in that).

For example, let's assume that a particular page at seagate.com
contains an offsite reference to nexus.ensighten.com. If the hosts
file contains "nexus.ensighten.com", then AFAICS the browser does
not need to bother with a DNS lookup.

The browser will always do a DNS lookup when it needs to. It doesn't
know anything about the hosts file (if it exists, or what's in it and
what's not in it, etc).

OTOH, if the hosts file contains only numeric IP addresses,
then a DNS lookup would be necessary to resolve the domain
name.

If I know that www.google.com resolves to 123.45.67.89, then if I have
this line in my hosts file:

123.45.67.88 www.google.com

Then my system would never perform an external DNS query for
www.google.com.