Here are the Best Practices and Troubleshooting articles which are related to GUP.

Group Update Provider: Sizing and Scaling Guidelines

http://www.symantec.com/business/support/index?page=content&id=TECH95353

Best Practices with Symantec Endpoint Protection (SEP) Group Update Providers (GUP)

http://www.symantec.com/business/support/index?page=content&id=TECH93813

Configuring the Group Update Provider (GUP) in Symantec Endpoint Protection 11.0 RU5

http://www.symantec.com/business/support/index?page=content&id=TECH96419&locale=en_US

Guide to create the GUP for remote location

https://www-secure.symantec.com/connect/downloads/create-gup-symantec-can-help-conserve-bandwidth-clients-remote-location

How to Setup a Group Update Provider (GUP)

http://www.symantec.com/business/support/index?page=content&id=TECH105005&locale=en_US

Tips For Installing SEP In A Low Bandwidth Environment

https://www-secure.symantec.com/connect/articles/tips-installing-sep-low-bandwidth-environment

Symantec Endpoint Protection (SEP) Group Update Providers (GUPs) Selection

https://www.symantec.com/business/support/index?page=content&id=TECH198702

Troubleshooting the Group Update Provider (GUP) in Symantec Endpoint Protection (SEP)

http://www.symantec.com/docs/TECH104539

How can we check which content SEP 12.1 clients are downloading from GUP?

https://www-secure.symantec.com/connect/articles/how-can-we-check-which-content-sep-121-clients-are-downloading-gup

How to confirm if SEP Clients are receiving LiveUpdate content from Group Update Providers (GUPs)

http://www.symantec.com/business/support/index?page=content&id=TECH97190

SEP Content Distribution Monitor (for GUP health-checking)

https://www-secure.symantec.com/connect/downloads/sep-content-distribution-monitor

How to analyze Debug logs from GUP to determine which clients are taking definitions from GUP

 https://www-secure.symantec.com/connect/articles/how-analyze-debug-logs-gup-determine-which-clients-are-taking-definitions-gup

Video’s created on Group Update Provider on the Symantec Connect website.

 https://www-secure.symantec.com/connect/videos/group-update-providers-part-1

https://www-secure.symantec.com/connect/videos/group-update-providers-part-2

GUP content monitoring tool video

https://www-secure.symantec.com/connect/videos/sep-content-distribution-monitor-introduction

Hope it can help to all.

Thanks

Sumit G.