Network segmentation in a small company: how many VLANs is too many
A single flat network is simple until the first incident. Five segments are enough for most organisations, provided that policy stands between them and not just a VLAN number.
Topics
Networking
The network is the layer everything else stands on, and yet it is usually designed once and not revisited for years. I write about segmentation that limits the impact of an incident, about DNS as a single point of failure, about firewalls between segments, and about link redundancy in organisations that have no dedicated network team.
Posts in this topic
All topicsDNS as a single point of failure: what breaks when the resolver stops answering
The ticket says „the network is down”, and the network is fine. Name resolution is not. Where DNS hides single points of failure, and how to design it so that the failure of one element goes unnoticed.
Two internet links in a small company: failover that actually fails over
The second link is often bought, plugged in and never tested. How to design the switchover so that it works on the day of the outage, and what will not switch by itself even with a perfect configuration.
Applications that still send mail over plain SMTP: an internal relay instead of exceptions
Older applications, printers and scripts send mail to port 25 with no encryption and no authentication. A cloud mail service will not accept that. One internal relay solves the problem better than twenty exceptions.