In the world of the internet, DNS (Domain Name System) plays an essential role, as it is responsible for converting the web addresses typed by users into IP addresses that computers can understand. However, issues such as DNS pollution and DNS hijacking often cause great inconvenience to users.

What is DNS Pollution?

DNS pollution, also known as domain name server cache poisoning, refers to the malicious alteration of a domain name server’s data packets, causing domain names to point to the wrong IP addresses. When users attempt to access a website, they might be wrongly directed to an entirely unrelated page. In this case, users are unable to reach their desired website even if the domain name is correct.

Distinguishing Between Domain Pollution and DNS Pollution

Before addressing DNS pollution, it’s important to determine whether it’s a case of domain pollution or DNS pollution. Domain pollution typically means that the domain name itself has been marked and is restricted. If it’s domain pollution, switching to a new domain might be the only solution. For DNS pollution, there are different handling methods.

How to Detect DNS Pollution?

To detect DNS pollution, you can use specialized query detection tools or the nslookup command in the command prompt. For example, use the command nslookup (where is the domain you want to check, and is a non-existent IP address). If it returns an IP address that doesn’t actually exist, it indicates that DNS pollution has occurred.

Strategies for Handling DNS Pollution

  • Immediately Stop Resolving: For minor pollution, pausing domain name resolution for a period may help in recovery.
  • Seek Professional Help: For more serious pollution, consider using professional DNS cleaning services. These services can identify and disregard polluted DNS responses without needing to change the domain name.
  • Change DNS Servers: For DNS hijacking, changing your system’s DNS settings to a trusted foreign DNS server can be a quick fix.
  • Use a Proxy or VPN: Although not a direct solution to DNS pollution, using a proxy server or VPN can circumvent local DNS resolution, thus reducing the impact of DNS pollution.
  • Ignore Specific IP Addresses: Sometimes, DNS pollution in certain countries uses fixed IP addresses. By knowing these IP addresses and configuring your system to ignore these specific responses, you can lessen the impact of DNS pollution.

Updating and Upgrading Defensive Measures

As internet security technology advances, we also need to update and upgrade our defensive measures. Here are some recommended prevention strategies for handling DNS pollution:

  • Use DNSSEC: DNSSEC provides a way to ensure that the DNS responses received are authenticated, effectively preventing DNS pollution.
  • Encrypt DNS Queries: Protecting DNS queries from being intercepted and altered can be achieved by using encryption protocols like DNS-over-HTTPS (DoH) or DNS-over-TLS (DoT).
  • Regular Monitoring and Auditing: Monitoring network traffic and auditing DNS query logs regularly can help to quickly identify and respond to potential DNS pollution incidents.
  • Establish Redundant Networks: Increasing network resilience and reducing reliance on single points of failure can be achieved by using multiple DNS service providers and setting up redundant DNS resolution paths.