Hi Sanjv
Before executing the backup command, are you able to browse the network share ('\\192.168.1.3\prd_bkp\PRD_backup_sybase_log\PRD_10102014_1053.dump)without provided any user id and password?
You can do one more thing from command prompt make the share location as a network drive letter and then try backup command
command prompt make the share to network drive letter S:
net use s: /delete
net use s: '\\192.168.1.3\prd_bkp\PRD_backup_sybase_log
Backup command
dump tran PRD to 's:\PRD_10102014_1053.dump'
Regards