In v6, /48 is the minimum prefix that can be advertised by the routers in the Internet.

I believe in v4, its /24.

Until yesterday I wasn’t aware of that. I might have thought you could even advertise one IP (ie. /128 or /32) but that’s not possible.

Ref: https://blog.apnic.net/2020/06/01/why-is-a-48-the-recommended-minimum-prefix-size-for-routing

namespaces is a Linux Kernel feature. There are different types of namespaces

• Partitions Kernel resources such that one set of Processes see a different resources while others different
• Apartment complex analogy - 7 different namespaces
• PID namespace - Watching TV show
• Net namespace - each namespace gets an unique IP address s list of port. - apartment address analogy
• Uts namespace - host names for Ip address - Telling taxi driver apartment name instead of address
• User namespace - Files are associated with VID Euser Identification
• Mailbox associated to apartment unit # not with the name of the person - Mit namespace o to isolate mount points such that processes in different namespaces cannot view each others files.
• Similar to chroot

Commands:

I have seen this term here and there. I remember fiddling with this in pain of setting up port forwarding in xfinity/.

DHCP - Dynamic Host Configuration Protocol (DHCP) is a network management protocol used on Internet Protocol (IP) networks for automatically assigning IP addresses and other communication parameters to devices connected to the network using a client–server architecture (from wiki )

client-server architecture? In a home network, router is the server and client is my PCs, laptops, Raspberry Pis etc.

I have used many signals with kill like SIGHUP, SIGKILL etc. Today I came across USR2.

Did a Google search and found the manual page from GNU. According to it,

These signals are used for various other purposes. In general, they will not affect your program unless it explicitly uses them for something.

Another one from the BSD mailing list

USR2 is a "user defined signal" (from "man signal")

It doesn't "mean" anything by definition.  Each application is free to define its meaning as it sees fit.  It's there specifically so that applications can use signals for special purposes without reusing the defined signals.

There are tools like https://tehnoblog.org/ip-tools/ip-address-in-cidr-range/ which does the job. It doesn’t support IPv6. One of my colleagues today taught me how to do it by hand quickly.

Say we have an IP 2b06:4600:1101:0:abcd:efa:dbd:ea60:f5a6 is in the CIDR 2b06:4600:1101::/64

First step is to check what’s the mask bits. Here it is 64. So you take the address, take the first 64 bits and see if they are the same as the CIDR.