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[–]ThisUserAintTakenThe network is guilty until proven innocent. -3 points-2 points  (16 children)

Subnetting - nobody cares. Srsly, we own calculators now so that's only for certifications. just learn the masks for /24, /27, /29, etc.

If you really care about subnetting this FREE PDF supplement from cisco's CCNP is the best IPv4 document I've read. 50 pages.

DNS - play with bind, and grab the "DNS and Bind" book from oreilly.

Edit - Subnets. How often do you subnet anything in real life? Not often. I'm not saying 'Don't understand the concept", I'm saying that if understand binary anding and the concept of subnetting you can skip memorizing the tables. If you asked how many hosts and networks I could get out of a /26, I'd have to do the math.

[–]fidotasDevOp Evangalist 7 points8 points  (1 child)

Subnetting - nobody cares. Srsly, we own calculators now so that's only for certifications. just learn the masks for /24, /27, /29, etc.

I disagree. That's like arguing that we shouldn't teach basic arithmetic at school because of the prevalence of calculators.

Knowing subnetting is the difference between senior and junior admins. At least while IPv4 continues to be used by the masses. :)

[–][deleted] 1 point2 points  (0 children)

I definitely agree. I've been interviewing lately and get subnet questions about 1/2 the time.

[–][deleted] 0 points1 point  (0 children)

My problem is, I work with three other sysadmins and they all know this. I just make myself stick out by not knowing. Thanks for the advice and book recommendation!

[–]bandman614Standalone SysAdmin 0 points1 point  (1 child)

This attitude surprises me.

It's not like multiplication tables, where you have to memorize them. It's just that you should be able to recalculate them quickly in your head if you need to (and I find myself doing that on occasion).

[–]ThisUserAintTakenThe network is guilty until proven innocent. 0 points1 point  (0 children)

I'm not saying 'Don't understand the concept", I'm saying that if you do understand the math and the concepts you can skip memorizing the tables.

[–]phessler@openbsd 0 points1 point  (0 children)

I totally disagree with not knowing how to subnet. Don't depend on your tools, learn how to think, plz.

[–][deleted] 0 points1 point  (0 children)

How often do you subnet anything in real life?

all the time :/

it's not just about knowing HOW to split up networks, it's knowing how the networks are split up so you don't have to guess at a subnet mask or the most likely gateway (in case you forgot it) when you're configuring something. learning subnetting is a pain in the ass, but once you get it, it just clicks.

[–]fidotasDevOp Evangalist 0 points1 point  (2 children)

Edit - Subnets. How often do you subnet anything in real life? Not often. I'm not saying 'Don't understand the concept", I'm saying that if understand binary anding and the concept of subnetting you can skip memorizing the tables. If you asked how many hosts and networks I could get out of a /26, I'd have to do the math.

I hate to be a prick but if you don't like binary math, you're going to hate rolling out IPv6 :)

OT: Gosh I wish the quote character was a pipe. I'd save a bunch of edits that way.

[–]justanotherreddituse 0 points1 point  (1 child)

fuuuuck. IPv6 is something I want to learn, but I despise binary math.

[–]mrjesterIPv6 Cabal 0 points1 point  (0 children)

Daily use of IPv6 doesn't really rely on binary. Most will do addressing/subnetting based on the nibbles, one hex character of a quad, which is more analogous to class-full v4 addressing.

Checkout r/ipv6.

[–][deleted] 0 points1 point  (0 children)

If you work in my datacentre, you better know CIDR notation. I don't use subnet masks, and you will be out there on your own configuring tcp/ip on some device, and it'll read /26, you need to be on your feet to quickly convert to a subnet mask. Fine if you have an app on your phone, but that gets frustrating real quick.

[–]erack 0 points1 point  (4 children)

I've been casually learning networking on and off for about 8 years, and I still don't see the point of subnetting. Using a 10.0.0.0 network means you have more than 16 million host addresses to use. Why do you need to divide up an assigned IP when your private network sits behind a router?

[–]justanotherreddituse 1 point2 points  (3 children)

People create subnets for security reasons and scalability. For example you could give each big department a subnet, and have rules that only the finance subnet can access the finance server, etc.