NSA CCC Protective Doman Name Service (PDNS+)

Citrix – Mitigate DNS DDoS attacks

Akamai – What Is a DNS DDoS Attack?

Cyber Security News – Top 10 Dangerous DNS Attacks Types and The Prevention Measures

Amazon Web Services – Configuring DNSSEC for a domain

Squid Cache

Microsoft – DNS Security Appliances in Azure

Cloudflare – What is DNS Filtering?

CISA – Strengthen Your Resolve – Understanding DNS Attacks