Posts tagged "networking"

Private network design basics

Last update: 2022-01-16.

Tags: networking

People without much networking experience may think that network design is something that is done for large organizations by highly experienced specialists with fancy titles, while small networks don't need any design at all. However, most networks start small and grow larger than anyone might have planned, and the "no design" approach quickly shows its limits. Worse yet, changing the design of a production network is much harder than building a network from scratch—even a very small network can take hours to reconfigure for a new addressing scheme and ensure that everything is working correctly. Luckily, if you know a few facts and principles, you can avoid most mistakes that take a lot of effort to fix. If you are starting a network and want to get it right, read on.

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CCNA 200-301

Last update: 2021-06-25.

Tags: networking, cisco

Today I passed Cisco's CCNA 200-301 certification exam. In short, they fixed a lot of old problems but added a few new ones. However, it's still much closer to an exam that a working network administrator can walk into from the street and pass, compared to the last time I've seen it. In this post I'll try to offer some preparation tips.

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Anycast routing

Last update: 2018-02-28.

Tags: networking, bgp

It is well known that due to limited practical size of a UDP packet that can be transmitted without fragmentation, the number of DNS root servers is limited to 13 addresses. There are indeed 13 root servers named from A to M (, and so on). However, if you visit, you can see that most of those servers somehow have dozens and even hundreds locations around the world. How is it possible for one server to have more than one location? The answer is anycast routing.

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