Backing up is a best way to revert your chances just like undo button. Most probably many webmaster don't forgot to take a backup of their sites regular basis. Every time you cannot believe your sites are always working without any obstructions. Just think if all of efforts on your website was completely removed by hackers or unfortunately Crashes happen what will you do? Before you stuck on any kind of vulnerabilities wisely take a back up, it's too better to store backup to Dropbox or any cloud storage than local server, that why? you can access your backup anywhere in the world at anytime. Some plugins are available for making automatic wordpress backup to Dropbox easily.
BackWPup Free - WordPress Backup Plugin
The best WordPress plugin to store backup to Dropbox for free, not just Dropbox you can use some external backup services for backup job. Few supported services such as S3 services, Microsoft Azure, Google Drive (pro version only). It enables complete automatic backup depending on schedule you chose. Which offers option for Instead of selecting core wordpress files, you can exclude the unnecessary folders you don't want. Whether you need additional features and good support let's purchase it's premium version as BackWPup Pro.
It is a premium premium by Matt founder of wordpress whereby this is more safe from hackers and viruses. It provides good set features such as daily backup,spam protection, malware protection, unlimited backup,automated restores, easy site migration. If you plan to purchase any plugin for backup service you can choose it.
Another wordpress plugin to do backup with Dropbox. Installation and configures are quite easy. In this plugin you cannot compress backup to be zipped, so may be take somehow extra time to backing up. But everything will be backed up including media, files and database. If you want to backup as zip should purchase premium extensions. Here also you can exclude undesired files and make scheduled automatic backup.
BackupBuddy is a great premium plugin it has more features such as complete back up, scheduled backups, exclude file and database, Backup Profiles and some. It offers quick backup feature able to backup in just 60 seconds. Send your backup to external storage such as Dropbox, Amazon S3, Racks pace, Cloud,email. This plugin has own storage called BackupBuddy Stash gives 1Gb space for free.
A free plugin but offers some features like other plugins. Free means you can only do backup, you must need pro version for send to cloud services. Ability to send automatic or manual backup to following external storage such as Dropbox, Email, Amazon S 3, Microsoft OneDrive and more. It notify to users through email after every backup process. You can perform custom backup for Both wordpress files, plugins, database. One more plugin suggestion for you
Good wordpress plugin gives many features without cost, to get started with this you must have a PressBackup account. It offers their own cloud Storage for free or send backup to these cloud services DropBox , Amazon S 3.