You clients get no Internet connection when using UCS as DNS server
Usually heavy load on the UCS server.
top might show high IO-Waits or
vmstat 1 1000 shows non-zero values for bi and/or bo.
Cache improves access times. with high bi and low bo values in vmstat it shows many read access and only few write access to the disk. In this case adding more memory (RAM) to the system might help to improve the services.
Add memory as long as “si” and “so” values are close to zero after a while.