In the internet infrastructure, DNS plays a crucial role in translating domain names into IP addresses. It's fair to say that without DNS, the internet would be virtually nonexistent. However, precisely because DNS is located at the core of the network access chain, attacks on it often lead to widespread website outages, data breaches, and even business disruptions. Therefore, understanding common DNS attack types and developing effective DNS resolution security protection solutions has become an important and indispensable topic in website operations and network security.

　　Why is DNS a vulnerable target? Traditional DNS protocols, in their initial design, prioritized availability and distributed scalability, with relatively limited consideration for security. For example, they default to using the UDP protocol, making source addresses susceptible to spoofing; early versions lacked identity verification and data integrity verification mechanisms; and the DNS query process is transparent to users, making attacks difficult to detect. These characteristics make DNS an ideal entry point for attackers to conduct traffic hijacking, information tampering, and denial-of-service attacks.

　　Common DNS Attack Types:

　　1. DNS Hijacking

　　DNS hijacking is the most common and widespread type of attack. Attackers manipulate DNS resolution results, redirecting users' access to domain names to malicious servers.

　　Common scenarios include: router intrusion and modification of local DNS configuration; malicious DNS being forcibly distributed via public Wi-Fi; DNS poisoning or man-in-the-middle attacks at the ISP level.

　　Harm: Users are redirected to phishing websites, malicious advertising is injected, and sensitive information such as account names and passwords is leaked.

　　2. DNS Poisoning

　　DNS poisoning, also known as DNS cache poisoning, refers to attackers injecting forged resolution records into DNS servers, causing incorrect IP addresses to be cached and remain effective for a long time.

　　Attack characteristics: Affects recursive DNS with "caching mechanisms"; after a successful attack, the impact can last for a long time; it is difficult for users to repair themselves.

　　Typical impact: A large number of users accessing the same domain name but experiencing incorrect resolution, cross-regional access anomalies, and websites being "misjudged as inaccessible".

　　3. DNS Amplification Attack

　　DNS amplification attacks are a variant of DDoS attacks. Attackers exploit the characteristic that DNS query responses are much larger than requests, creating massive traffic to overwhelm the target server.

　　Attack Flow Summary: The attacker forges the victim's IP address, sends a small query to an open DNS server, and the DNS server returns a large response to the victim.

　　Characteristics: Low cost, high amplification factor, instantaneous surge in traffic, easily causing network congestion.

　　4. DNS Tunneling Attack

　　DNS tunneling is a relatively covert attack method. Attackers encapsulate data within DNS queries and responses, thereby bypassing firewalls and security audits.

　　Common Uses: Data leakage, remote control (C2 communication), bypassing corporate network access restrictions.

　　Difficulty: The DNS traffic itself is legitimate, and the encrypted or obfuscated domain name is difficult to identify.

　　5. DNS Spoofing

　　DNS spoofing is often combined with man-in-the-middle attacks. Attackers forge responses during communication between the user and the DNS server, preemptively returning incorrect resolution results.

　　Attack Conditions: Located on the same local area network, able to listen to or predict DNS requests. Although this type of attack has high environmental requirements, it still poses a certain risk in insecure networks.

　　DNS Resolution Security Protection Solution:

　　To address the attack types mentioned above, single protection methods are often ineffective. In practice, a comprehensive "multi-layered protection" strategy should be adopted.

　　1. Enable DNSSEC (Domain Name System Security Extension). DNSSEC provides source verification and integrity checks for DNS data through a digital signature mechanism. Its core advantage lies in preventing DNS pollution and forged responses, improving resolution credibility, and being transparent to users without requiring additional operations. Although DNSSEC deployment is costly, it is still a worthwhile security measure for core business domains.

　　2. Use a trusted recursive DNS service. Choosing a DNS service provider with high security and strong attack resistance can significantly reduce attack risks. Recommended features include support for DNSSEC verification, DDoS protection capabilities, global Anycast node deployment, and avoiding the use of DNS from unknown sources or with low public security in enterprise and server environments.

　　3. Deploy intelligent DNS and multi-line resolution. Intelligent DNS dynamically returns the optimal IP based on the user's origin and network quality, which can reduce the impact of resolution anomalies to a certain extent. Additional advantages include improved access speed, automatic failover, and reduced single point of failure risk.

　　4. Strengthen DNS server self-protection. If the enterprise has its own DNS service, it should focus on disabling recursive queries (open only to authorized users), limiting response rates to prevent amplification attacks, regularly updating DNS software versions, and enabling log and abnormal traffic monitoring.

　　5. Adopt encrypted DNS technology. DoH and DoT effectively prevent man-in-the-middle eavesdropping and tampering by encrypting the DNS query process. Applicable scenarios: public networks, businesses with high privacy requirements, and prevention of local DNS hijacking.

　　Practical suggestions for building a complete DNS security system:

　　In actual operation and maintenance, DNS security should not be a "temporary patch" but should be integrated into the overall network security architecture.

　　Pre-emptive protection: secure configuration + authoritative DNS hardening

　　In-process monitoring: real-time resolution monitoring, anomaly alerts

　　Post-incident recovery: rapid DNS switching, cache clearing

　　Only through the combination of systems, technologies, and processes can the business risks brought by DNS attacks be truly reduced.

　　Although DNS may seem like just a basic service of "resolving domain names," its security is directly related to the stability and trustworthiness of the entire Internet access link. From DNS hijacking to amplification attacks and then to covert tunnel communication, attack methods are constantly evolving, placing higher demands on protection solutions. Only by deeply understanding common DNS attack types and combining them with multiple protection measures such as DNSSEC, encrypted resolution, and multi-node deployment can a stable, secure, and sustainable DNS resolution system be built to safeguard websites and businesses.