Need some advice on learning networking

[BillyCarpenter]

Now you can understand how you can have only one public IP address (assigned to your modem), and set up a production network as well as a guest network, giving them both internet access and not having them be able to see each other.

This is quite common in a lot of businesses; for instance, the dealership I bought my car from has a guest network set up for customers, while still maintaining a business network for the employees. All from one IP address assigned by their ISP.

BTW...you'd be surprised how many IT admins (mostly noobs) don't understand this concept; I've had more than my fair share of 'em.

Ken,

You've been a big help to me. More than you'll ever know. I can't thank you enough.

EDIT: And yes, I understand how the public IP address of the router works. The way it was explained to me is that back in the day "they" used think that every computer would need it's own unique IP address to communicate on the internet. They realized there wasn't enough IP address to go around so they solved that problem with something called NAT'ing. I won't bore with with the specifics, I know you know this.

[KenB]

Ken,

You've been a big help to me. More than you'll ever know. I can't thank you enough.

EDIT: And yes, I understand how the public IP address of the router works. The way it was explained to me is that back in the day "they" used think that every computer would need it's own unique IP address to communicate on the internet. They realized there wasn't enough IP address to go around so they solved that problem with something called NAT'ing. I won't bore with with the specifics, I know you know this.

You're quite welcome, my friend. Glad to help!

[KenB]

So, over the past few days I've spent a lot of times learning about routers and what they do. I used to think all they did was connect to the internet but it turns out they do WAAAAAYYYY more than that. One thing they can do is make it possible for computers to communicate that are on different local networks. They're also responsible for DHCP and you can even set the length of the lease time. You can set the IP range for DHCP and there are other things but I won't bore yall.

Somehow in my study of routers it led me subnet masking. I never knew what those numbers meant and didn't understand the purpose. But I understand it perfectly now. I spent way too much time on this. I don't know how much I'll ever use this knowledge but at least I can look at the subnet and understand if it's a Class A, B or C network. And I even know which part of the IP address deals with the network part or the number of hosts. My gut feeling is that I probably will never be assigning subnets...I'll just be plugging in the numbers that someone else set but it's comforting to understand how it works.

Along those lines, I once had a university as a customer (back in the late '90s) who did all DHCP with NO reservations. It was a pain in the keester to get your MAC address(es) registered with them, but the process worked. If your device wasn't registered, you got no address, even if you set one statically.

They had a full Class B block of addresses available (so 64,000+) but they were running short. There were only about 11,000 nodes active at any given time,(which fluctuated a lot when semesters started and ended) but they had a problem with folks not cancelling MAC addresses when they added new equipment, such as new desktops or laptops, or replaced network cards. (Keep in mind that this was well before the dawn of mobile devices.)

I had about 100 Canon MFPs there, including about 5 Fieries. All of them were printed to using hostnames.

They would have been in deep doo-doo had each node required a dedicated address.

[slimslob]

So, over the past few days I've spent a lot of times learning about routers and what they do. I used to think all they did was connect to the internet but it turns out they do WAAAAAYYYY more than that. One thing they can do is make it possible for computers to communicate that are on different local networks. They're also responsible for DHCP and you can even set the length of the lease time. You can set the IP range for DHCP and there are other things but I won't bore yall.

Somehow in my study of routers it led me subnet masking. I never knew what those numbers meant and didn't understand the purpose. But I understand it perfectly now. I spent way too much time on this. I don't know how much I'll ever use this knowledge but at least I can look at the subnet and understand if it's a Class A, B or C network. And I even know which part of the IP address deals with the network part or the number of hosts. My gut feeling is that I probably will never be assigning subnets...I'll just be plugging in the numbers that someone else set but it's comforting to understand how it works.

I had an elementary school district, K through junior high, that had 7 campuses, the bus garage, the ware house/print shop, the main office and the IT office/main servers scattered around the city. Each location had its own subnet. So you never know when knowledge of subnets will come in handy.

Their IT was very good. He even took care of some of the minor paper jam problems on the copiers. Teachers had to provide their own paper so there were a few loading problems.

[BillyCarpenter]

Along those lines, I once had a university as a customer (back in the late '90s) who did all DHCP with NO reservations. It was a pain in the keester to get your MAC address(es) registered with them, but the process worked. If your device wasn't registered, you got no address, even if you set one statically.

They had a full Class B block of addresses available (so 64,000+) but they were running short. There were only about 11,000 nodes active at any given time,(which fluctuated a lot when semesters started and ended) but they had a problem with folks not cancelling MAC addresses when they added new equipment, such as new desktops or laptops, or replaced network cards. (Keep in mind that this was well before the dawn of mobile devices.)

I had about 100 Canon MFPs there, including about 5 Fieries. All of them were printed to using hostnames.

They would have been in deep doo-doo had each node required a dedicated address.

I keep hearing how unreliable DHCP is and not to use it, but, like in your scenario, what if there are a thousand(s) devices on the network? I can't imagine having to physically assign a dedicated address to all of 'em. So, I'm thinking there must be some way to make DHCP reliable. I could be wrong.

[slimslob]

Along those lines, I once had a university as a customer (back in the late '90s) who did all DHCP with NO reservations. It was a pain in the keester to get your MAC address(es) registered with them, but the process worked. If your device wasn't registered, you got no address, even if you set one statically.

They had a full Class B block of addresses available (so 64,000+) but they were running short. There were only about 11,000 nodes active at any given time,(which fluctuated a lot when semesters started and ended) but they had a problem with folks not cancelling MAC addresses when they added new equipment, such as new desktops or laptops, or replaced network cards. (Keep in mind that this was well before the dawn of mobile devices.)

I had about 100 Canon MFPs there, including about 5 Fieries. All of them were printed to using hostnames.

They would have been in deep doo-doo had each node required a dedicated address.

It doesn't have to be a large campus for print by hostname to be helpful. I had a doctor who liked to change his ISP and therefore the subnet frequently.

[bsm2]

I keep hearing how unreliable DHCP is and not to use it, but, like in your scenario, what if there are a thousand(s) devices on the network? I can't imagine having to physically assign a dedicated address to all of 'em. So, I'm thinking there must be some way to make DHCP reliable. I could be wrong.

Nothing wrong with DHCP
Normally Server, printer and copy machines have static IPaddress
You just need to know how it works

[BillyCarpenter]

Nothing wrong with DHCP
Normally Server, printer and copy machines have static IPaddress
You just need to know how it works

Understood. But what if an organization has 300 copiers and desktop printers. Are they gonna assign a static IP address to all of 'em? Honest question. I have no idea.

[bsm2]

Understood. But what if an organization has 300 copiers and desktop printers. Are they gonna assign a static IP address to all of 'em? Honest question. I have no idea.

A company that size would have mult subnets and DHCP reservations.

[keithxxiii]

I am currently assigned to a client with 1800+ devices in different branches across the county. All devices' IP addresses are assigned by DHCP servers. Such a pain to manage since we are rebuilding a fleet management software. You have to specify which ports are required since the firewalls are controlled by the security team.
I was then forced to simulate the scenario in my own virtual lab along with PFSENSE as a firewall to simulate port traffic and blocking.