[Malevolence]

I would imagine that most companies would maintain multiple hosts, broken apart by department or project or whatever, and that public hosts (which invite marks from the general public so that they can access them for things like shopping, etc) would be separate. Having a host within a host may or may not be possible (it seems unlikely), but it doesn't matter since no matter where a host is located it is accessible from any grid, and therefore would not provide any layering of security.

Now, there is nothing to prevent a host from running silent, and since they can be anywhere, spotting one with a matrix perception check would be all but impossible without some prior knowledge of where to start looking.

[wired]

Now, there is nothing to prevent a host from running silent, and since they can be anywhere, spotting one with a matrix perception check would be all but impossible without some prior knowledge of where to start looking.

Am I reading the Matrix Spotting Table on page 234 incorrectly?  It appears that Hosts do not have a "Running Silent" option, only a "Not Running Silent" option which incurs the following:  "Automatically Spotted".

I would interpret that to mean that hosts cannot be hidden -- they're automatically detected.

[Xenon]

Do you envision separate Hosts for Human Resources and Security Resources?

I would imagine that most corporations would probably just have one private host and put everything in it.
Maybe a separate host for their underground top-secret facility
(but if they want to keep their underground top-secret facility top-secret they they probably run everything down there on wires rather than wireless).

...would be all but impossible without some prior knowledge of where to start looking.

with a physical direct connection to a slaved device slaved you get a mark on both the slave and its master.
you automatically spot anything within the matrix you got a mark on...

without a physical connection to a slaved device you can probably just ask your GM;
"I am trying to spot the master [device or host] that this device is slaved to"

A technomancer could have her Courier Sprite use it's Cookie Power on a persona of an employee
- And have it record all Hosts the persona Enter.

[Malevolence]

Now, there is nothing to prevent a host from running silent, and since they can be anywhere, spotting one with a matrix perception check would be all but impossible without some prior knowledge of where to start looking.

Am I reading the Matrix Spotting Table on page 234 incorrectly?  It appears that Hosts do not have a "Running Silent" option, only a "Not Running Silent" option which incurs the following:  "Automatically Spotted".

I would interpret that to mean that hosts cannot be hidden -- they're automatically detected.

Core, p 235:

For all intents and purposes, there is no “physical”
distance to any host in the Matrix. You can always spot a
host from anywhere on the planet without a test, assum-
ing the host isn’t running silent.

Of course, with no "physical" distance to any host, a host running silent (indeed all hosts) would then be within 100 meters of you as far as a matrix perception test (and noise) is concerned, and thus would effectively return a false positive (for lack of a better term) for any search you ever did for icons running silently. So I suspect that a host running silently would have to be considered outside of 100 meters of you for purposes of searching for icons that are running silent.

Spotting a hidden host could be as easy as doing an opposed test against the host by "knowing" something about it (like that it is an Ares black ops host running silent), or as hard as requiring you to physically travel to within 100 meters of its "physical" location or requiring a mark on it or something in it (similar to getting a file out of a host archive). Until the matrix supplement comes out, it's up to the GM. The option they choose would depend on how they interpret the matrix perception text where they describe the ability to detect unknown icons running silent within 100 meters, but don't necessarily state that there is a distance limit to locating an icon that is running silent once you know something about it.

[Xenon]

It's the same test to spot an icon running silent beyond 100 meters as it is to spot an icon running silent within 100 meters (or if the icon does not have a physical location at all).

Beyond a distance of 100m you just have some extra noise to deal with. If you are not on the same grid, you use the public grid or the target is on a public grid you might get a negative dice pool modifier there as well. You get a positive dice pool modifier if you are in hot-sim or if you are a Technomancer etc etc. But how the test to find a silent running icon is resolved have nothing to do with physical distance...