Endpoint Protection

I've been reading contradicting explanations on the delta updates.  I'd like to have this clarified.

I have 5,000 clients.  Currently configured with 1 LUA Server and 2 SEPM's which have sql installed on each.
For my LiveUpdate Policy that is configured in the SEPM, I have both boxes checked as shown below.  I blurred out our server info.

When the clients check in, what is the first attempt?  The SEPM or the internal LiveUpdate Server?  It does say, if both boxes are selected that the clients with use both servers.  Just want to know which has more weight?

Does the internal live LiveUpdate server update the clients using delta's?  This is the question where I've read yes and no. This is the most important question as this would make me Not want to use a LiveUpdate server if it does not use deltas.

And yes, I have 1 GUP set up for my very remote location.  Our networking department wanted me to use a LiveUpdate Server so I can have more control over the time at which the clients download updates as to limit the amount of bandwidth used during peak hours.

Thank you!

When the clients check in, what is the first attempt?  The SEPM or the internal LiveUpdate Server?  It does say, if both boxes are selected that the clients with use both servers.  Just want to know which has more weight?

there is no priority, if the LU is triggered ,the client will contact internal Live update administrator.

If the client's heartbeat is triggered then the client will contact the SEPM.

Does the internal live LiveUpdate server update the clients using delta's? 

Yes, the LUA can provide the incremental updates to client

check this link

http://www.symantec.com/business/support/index?page=content&id=TECH154896

it's good to have GUP configured at remote locations for the bandwidth usage.

Q: When the clients check in, what is the first attempt?

Use the default management server [SEPM server] is the first source for the clients.

AS per the Liveupdate policy setting you configured

1st Priority goes to SEPM, If SEPM is not available then only it move on to  Internal Liveupddate server

Q: Does the internal live LiveUpdate server update the clients using delta's?

A:  LUA will provide Delta's [Thanks for the update @pete]

Suggestion:

You can implement multiple GUPS on every location and you can increase the content revisions as well on the SEPM. So Delta's will be available for the Clients. It will reduce the Network Bandwidth issue.

If you configure the GUP on the network then the clients contact:

1st source as GUP 

If GUP not available then clients move on to 

2nd Source as SEPM Server

If SEPM not available then clients move on to 

3rd Source Internal/External Liveupdate Administrator

This how Liveupdate designed to work.