Globe Ed Network Fundamentals

https://www.globed.net/courses/back-to-networking-basics

In this Networking Basics Workshop we will be learning the following:

REFERENCE MODELS
ETHERNET STANDARDS AND SPECS
TRANSMISSION METHODS
TOPOLOGIES
 NETWORKING DEVICES
IPV4 ADDRESSING
HEX CONVERSION
CISCO ROUTER AND SWITCH BASIC
CISCO ROUTER AND SWITCH CONFIGURATION
LAYER 2 SWITCHING  
LAYER 3 ROUTING
LAYER 3 ROUTING USING L3 SWITCHING

RECORDINGS OF THE WORKSHOP WILL BE SENT TO ALL THAT REGISTER – Even to those that could not attend

A tool to find out if BGP is lying to you

APNIC has a bog article on detecting “bgp lies”.

https://blog.apnic.net/2021/05/24/a-tool-to-detect-bgp-lies/
Do you ever wonder whether you can really trust other networks, such as your provider(s) and peers? More precisely, wouldn’t you like to be able to tell if the traffic you send always flows through the paths received in the Border Gateway Protocol (BGP)? Could it be that, for some prefixes, the forwarding path might differ?

Interconnection Quarterly

https://static1.squarespace.com/static/5e013aba1c79407e08cf53bc/t/60610a0a5517c019d36a2083/1616972299607/Foundations+-+Interconnection+Quarterly+%284Q2020%29+.pdf

From Christian Koch from Foundations

I am excited to reveal that my quarterly interconnection update has
transformed into the Interconnection Quarterly, a hand-tailored,
independent briefing on the interconnection industry. Right now, my plans
are to publish the Interconnection Quarterly shortly after the last public
companies report earnings, as I’ve done with the previous updates. This
may change in the future, but for now, this is the plan.
In this inaugural issue, you’ll find the latest financial and business metrics
for select data center operators and interconnection platforms, as well as
insights into key developments and newsworthy events that occurred
within the fourth quarter of 2020.
We’re at an important juncture for interconnection, and while it still may
be seen by some as just a basic service that a data center or colocation
provider must offer, the truth is, that interconnection is much more
important.
From cross-connects to cloud networks, the constant here is in the
connection. How that connection is established and what you can do
with it is what’s changing as we adapt to a world powered by software in
the cloud.

Bind 9.4 helpful notes

So recently I was spinning up some new authoritative names servers. I have stuck with bind for authoritative for years because the format of the files and queries is THE standard for DNS zones. IMHO, there are some better resolvers out there but I stick with bind for authoritative.

Anyway, on to my issue. The purpose of one of these servers was for reverse DNS. I added the in-addr files and added a few zone files. Things hummed along for a few days and the server went through an update and the authoritative stuff stopped working. After some digging here is what I found.

Bind 9.4 introduces a new option called

allow-query

allow query has specifically to do with the ability to query the namesever for records it is authoritative for. If that option is not there it will deny queries. Once I added the following code things started working correctly.

allow-query {any;};

A few later I come back to a different machine to troubleshoot an issue with a customer PTR record and found the log files were filling up with cache-denied messages. this was fixed by adding the two lines of code below.

additional-from-auth no;
additional-from-cache no;

In this case, some of the IP space still had servers pointing to it, most likely due to the domain holder going offline or out of business.