How to secure website from DDOS attack?

What exactly do you mean with "invalid traffic"?

https://www.cloudflare.com/ offers an anti-DDOS service and there are more companies that do such. Ask the company hosting your site for advice. But it isn't free.

However, let me note that having a DDOS-attack on your site, doesn't make your site is unsafe. Just unreachable. Your content is secure.

A web application firewall (WAF) can help detect and block DDoS attacks. It acts as a layer of protection between the hosting server and site visitors will ensure all malicious HTTP/HTTPS traffic is filtered and blocked.

A Denial of Service (DoS) attack is a malicious attempt to reduce a targeted system's accessibility to authorized end users, such as a website or application. Attackers frequently produce a lot of packets or requests, which eventually overwhelm the target system. In the event of a Distributed Denial of Service (DDoS) attack, the attacker creates the attack using numerous compromised or controlled sources.
DDoS attacks can generally be classified according to the layer of the Open Systems Interconnection (OSI) model that they target. The Network (Layer 3), Transport (Layer 4), Presentation (Layer 6) and Application (Layer 7) Layers are where they are most frequently found.
Reduce attackable surface area to limit attacker options and enable the construction of defences in a single location is one of the first methods to reduce DDoS attacks. We must make sure that no ports, protocols, or applications are opened up for our application or resources from which they do not anticipate receiving any communication. reducing the potential attack points and enabling us to focus our mitigation efforts. You can sometimes achieve this by routing direct Internet traffic to specific components of your infrastructure, such as your database servers, and hiding your processing resources behind Content Distribution Networks (CDNs) or Load Balancers. In some circumstances, you can use firewalls or access control lists (ACLs) to regulate what

Securing your website from a DDOS attack can be a difficult task, but it is possible if you take the necessary steps. The first step is to identify the type of attack that is occurring. There are two main types of DDOS attacks: volumetric and protocol-based.

Volumetric attacks are the most common and are used to saturate the target website with traffic, slowing down the website or preventing access to it altogether. Protocol-based attacks are used to exploit weaknesses in application protocols, such as HTTP and FTP.

Once you know the type of attack, you can begin to take the necessary steps to protect your website. Some steps you can take include:

1. Install a web application firewall (WAF) to help filter out malicious requests.
2. Invest in a reliable server and hosting service that can handle large volumes of traffic.
3. Implement CAPTCHA on your forms to prevent automated scripts from submitting requests.

Monitor your network traffic regularly and set up alerts for suspicious activity.