If you come across an issue with AV DAT download failing and if the MDC logs don't show any failures and no network connectivity issues found, you can run the Full DAT download manually from CLI.
By Design AV does incremental updates on DAT, If its failing, we can now run the full DAT download from CLI.
Steps to follow to manually force a full DAT download:
Download Putty from internet
Login to putty giving you ip address of email security server and port 22
At the login prompt type “snwlcli”
Then type the admin username and password for the Web interface
You should get a “SNWLCLI:>” prompt
SNWLCLI:> stop thumbupdater
SNWLCLI:>forcemcafeeupdate ( forcecyrenupdate, if issue is with Cyren. forcevadeupdate, if issue is with Vade)
Once you run these commands give it 3-5 mins and check the MlfAVutil.log and it will show DAT <number> ( this number will change depending on which DAT number failed for that day) downloaded successfully and also show the test engine ran successfully.
This message is confirmation that force update worked.