If you running a web server, you should look into to cloudflare. https://www.digitalocean.com/community/questions/does-digital-ocean-comes-with-anti-ddos-protection

There are also other 3rd party DDoS migration services, which works as a proxy and it will filter incoming connections to your server. You have to keep your backend ip address as a secret. Downside with this is, they are usually expensive and adds latency.

Depends on what your trying to protect. What service is getting ddosed?