
We are very excited to announce the official release of Foundation DNS, with new advanced nameservers, even more resilience, and advanced analytics to meet the complex requirements of our enterprise customers. Foundation DNS is one of Cloudflare's largest leaps forward in our authoritative DNS offering since its launch in 2010, and we know our customers are interested in an enterprise-ready authoritative DNS service with the highest level of performance, reliability, security, flexibility, and advanced analytics.
Starting today, every new enterprise contract that includes authoritative DNS will have access to the Foundation DNS feature set and existing enterprise customers will have Foundation DNS features made available to them over the course of this year. If you are an existing enterprise customer already using our authoritative DNS services, and you’re interested in getting your hands on Foundation DNS earlier, just reach out to your account team, and they can enable it for you. Let’s get started…
From an end user perspective, DNS makes the Internet usable. DNS is the phone book of the Internet which translates hostnames like www.cloudflare.com into IP addresses that our browsers, applications, and devices use to connect to services. Without Continue reading

Let’s Encrypt, a publicly trusted certificate authority (CA) that Cloudflare uses to issue TLS certificates, has been relying on two distinct certificate chains. One is cross-signed with IdenTrust, a globally trusted CA that has been around since 2000, and the other is Let’s Encrypt’s own root CA, ISRG Root X1. Since Let’s Encrypt launched, ISRG Root X1 has been steadily gaining its own device compatibility.
On September 30, 2024, Let’s Encrypt’s certificate chain cross-signed with IdenTrust will expire. After the cross-sign expires, servers will no longer be able to serve certificates signed by the cross-signed chain. Instead, all Let’s Encrypt certificates will use the ISRG Root X1 CA.
Most devices and browser versions released after 2016 will not experience any issues as a result of the change since the ISRG Root X1 will already be installed in those clients’ trust stores. That's because these modern browsers and operating systems were built to be agile and flexible, with upgradeable trust stores that can be updated to include new certificate authorities.
The change in the certificate chain will impact legacy devices and systems, such as devices running Android version 7.1.1 (released in 2016) or older, as those exclusively Continue reading

All the Kubernetes Ingress videos from the Kubernetes Networking Deep Dive webinar with Stuart Charlton are now public. Enjoy!
A lot of people are spending time thinking about how to make transport and control plane protocols more energy efficient. Is this effort worth it? What amount of power are we really like to save, and what downside potential is there in changing protocols to save energy? George Michaelson joins us from Australia to discuss energy awareness in protocols.
I decided not to get involved in the EVPN-versus-LISP debates anymore; I’d written everything I had to say about LISP. However, I still get annoyed when experienced networking engineers fall for marketing gimmicks disguised as technical arguments. Here’s a recent one:
I decided not to get involved in the EVPN-versus-LISP debates anymore; I’d written everything I had to say about LISP. However, I still get annoyed when experienced networking engineers fall for marketing gimmicks disguised as technical arguments. Here’s a recent one:
At this stage of the build internally there is only really the bedroom, snags and trims (windows, ceiling edges and doors) left to do. I am currently in Australia having a bit of RnR so this is a reflective post to show the build at its present state and go through the things I have learnt along the way. I could plan all I like but as I haven’t lived on a boat before there was always going to be a few wrong design decisions.
Dmitry Perets wrote an excellent description of how typical firewall cluster solutions implement control-plane high availability, in particular, the routing protocol Graceful Restart feature (slightly edited):
Most of the HA clustering solutions for stateful firewalls that I know implement a single-brain model, where the entire cluster is seen by the outside network as a single node. The node that is currently primary runs the control plane (hence, I call it single-brain). Sessions and the forwarding plane are synchronized between the nodes.
Dmitry Perets wrote an excellent description of how typical firewall cluster solutions implement control-plane high availability, in particular, the routing protocol Graceful Restart feature (slightly edited):
Most of the HA clustering solutions for stateful firewalls that I know implement a single-brain model, where the entire cluster is seen by the outside network as a single node. The node that is currently primary runs the control plane (hence, I call it single-brain). Sessions and the forwarding plane are synchronized between the nodes.
In the previous three parts, we learned about all the interesting things that go on in the PHY with scrambling, descrambling, synchronization, auto negotiation, FEC encoding, and so on. This is all essential knowledge that we need to have to understand how the PHY can detect that a link has gone down, or is performing so badly that it doesn’t make sense to keep the link up.
The function in 1000BASE-T that is responsible for monitoring the status of the link is called link monitor and is defined in 40.4.2.5. The standard does not define much on what goes on in link monitor, though. Below is an excerpt from the standard:
Link Monitor determines the status of the underlying receive channel and communicates it via the variable
link_status. Failure of the underlying receive channel typically causes the PMA’s clients to suspend normal
operation.
The Link Monitor function shall comply with the state diagram of Figure 40–17.
The state diagram (redrawn by me) is shown below:

While 1000BASE-T leaves what the PHY monitors in link monitor to the implementer, there are still some interesting variables and timers that you should be Continue reading