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DNS best practices

You cannot imagine the internet without DNS. There is almost no service that doesn’t depend on DNS technology. E-mails, VoIP, web services, all kind of CRM and ERP systems and much more. DNS is so important that we must take care of our network and make it as secure as possible.

Here we will show you some good practices to manage your DNS. Prevention is the best defense. Pay attention to these pieces of advice and take action.

Hide the master DNS

Configure the master DNS as a hidden. Like this, it will not be shown in the records of the name server. It will not appear, and it will not respond to any queries. Its purpose will be to give zone transfers to secondary name servers which will be public but doing it safely and hidden.

Secured Access

Make the connection between the master DNS and the secondary name servers secured. Use ACLs (access control lists) and TSIGs (Transaction signatures). Like this, your secondary servers won’t be fooled, and your network won’t get corrupted.

Disable recursion

Do this on the external servers and reduce the risk for your authoritative servers to be part of DNS attacks like DNS Amplification.

Add rate limits

Even if you disabled the recursion on your authoritative DNS servers, they still could be used in DNS Amplification attacks with your domain names. To mitigate the options of the DNS attackers, you can add rate limits. If you are using bind software, here is an example configuration you can add to the options clause to set rate limit from 2 queries per second on average for each IPv4 class C (/24) network:

rate-limit {
responses-per-second 2;
ipv4-prefix-length 24;
slip 1;

Don’t show all information

The information about the version of your DNS software is for you. Don’t make it public. If hackers know it, they can use it against you by exploiting the particular vulnerabilities that the software might have. For example, if you are using bind software you can add a version in the options clause like this:

version “unknown”;

Place content (web) servers where your customers are

Be smart and think about your users. Place name servers where your clients need them the most. It will reduce the latency and improve the experience for your users. It will also minimize the load on your other servers, give you extra protection, and it will reduce the chance of failure. If you have multiple target markets in different locations (for example EU and the US), you can use GeoDNS service to direct the customers to the right servers which are closer to them.

Anycast DNS

Use Anycast DNS for your business. This will make the experience for your users, faster and better. It will dramatically reduce the time to load the first page of your website, which helps your SEO significantly. It makes it more resilient, making it harder to experience a down time and more protected from DDoS attacks because of the different points of presence.

You can read more about Anycast here and learn more how it is useful for your company’s network and what configuration suits you best.

These are some of the most recommended DNS practices. While there will be new threats, many of the DNS attacks happening these days can be evaded. No matter if your network is small or large, try to keep it safe and protected, by following our recommendations. Restrict access to some parts of the network, and remember that well-designed infrastructure is vital to your digital presence.

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Tags: , , , , , , Last modified: July 19, 2021