All networking info is in this thread

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Rob
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All networking info is in this thread

#1 Post by Rob »

Some basic networking things:

1) A LAN stands for local area network (your home or business network for sharing files or other things like or email, printing)

2) A MAN stands for metropolitan area network (if you have a company that has 2 locations in different towns for example) you would have a wire going from one location over to the other and you would have two separate subnets on each end

3) A WAN is a wide area network. For my computer to communicate to a computer on the other side of the world it would have to go through the WAN.

4) A subnet is the actual IP network makeup. For example if I have three locations connected to each other via VPN I would need three subnets (one for each location) (192.168.0.x, 192.168.1.x and 192.168.2.x for example)

5) A host is anything that takes up an IP address (computer, server, router, printer etc...)

6) There are 5 kinds of networks address’s that are categorized by class
a. 1 – 127 (0.0.0.0 – 127.255.255.255) (16,777,214 hosts/subnet)
b. 128 – 191 (128.0.0.0 - 191.255.255.255 (65,534 hosts/subnet)
c. 192 – 223 (192.0.0.0 – 223.255.255.255) (254 hosts/subnet)
d. 224 – 239 (224.0.0.0 – 239.255.255.255) - Muticast
e. 240 – 255 (240.0.0.0 – 255.255.255.255) - Reserved

7) For all practical purposes you won’t ever use class D or E IP addressing because you wouldn’t get enough usable hosts out of it even if you subnet the heck out of it.

8 ) For each class there is a dedicated private IP range (used for a LAN for example). Those are the following:
a. For a private class A network you would use the following: 10.x.x.x (a lot of HUGE corporations use this because they want to be able to segment off hundreds or thousands of separate networks around the world) (10.0.0.0, 10.1.0.0, 10.2.0.0 etc...)
b. For a private class B network you would use the following: 127.x.x.x (a lot of basic to moderate sized companies use this as their IP scheme) They use this because a lot of times they need to have more than 254 hosts.
c. For a private class C network (most common) you would use the following: 192.x.x.x (a lot of basic home networks are 192.168.x.x). Don’t ask me where the 168 comes from, that’s just what is used). With this kind of network you are limited to 254 hosts.

9) You’ll notice that your WAN IP (you can get this from going to http://www.whatismyip.com) is a class A IP address. This is because there is an abundance of these available.

10) There are only 254 class C privite IP’s available!! Big colleges such as MIT and other big companies like NASA and the US government own most/all of these. It would cost millions or billions of dollars to purchase a PUBLIC class C IP address.

The next thing on the list is probably subnetting but that topic will make most heads spin so I’m going to forget about that for now and zoom past that and on to DNS.

1) DNS stands for domain name system.

2) DNS is simpler than most think. – All it does it take a name and turn it into an IP address and vise-versa (reverse DNS).
a. For example robsnetworks.com translates to 74.94.97.165. (you can look up any domain name to find out the IP using a public lookup system such as http://www.network-tools.com.
b. 74.94.97.165 is the IP address that I pay for from Comcast, who in turn pays ATT or whoever the backbone provider is (I’ll explain that in detail later)
c. If the DNS server that is taking the request for “robsnetworks.com” goes down then you could simply type 74.94.97.165 right into the browser windows and potentially get the website (if it is set up that way).

3) Reverse DNS takes an IP address (74.94.97.165 again for example) and pulls up a simple database and will see that there are x number of websites associated to that address

4) Without DNS the internet WOULD NOT run.

5) There are 2 ROOT DNS SERVERS in the world that have ALL of the information about EVERY DOMAIN NAME EVER CREATED. For more info on the root servers check this out here: http://en.wikipedia.org/wiki/Root_name_server
a. A domain name is created through a registrar such as godaddy.com (hence the term buying a domain name)

6) If those root DNS servers ever go down then other secondary and tetrinary DNS servers can kick in and take the load.


I am done for now and will add more later. Is anyones head spinning yet :spinny: ? I LOVE THIS STUFF!!!!!! :boing:
~Rob - Rugged Depot
~Cell: (630)/300-8877~
~Owner - Toughbooktalk~
~Fully rugged Toughbook user since April 18th 2005~
~FZ-55 - Primary Toughbook / Workstation
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http://www.toughbooktalk.com
http://downloads.toughbooktalk.com/
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~Emergency preparedness starts with reliable communication systems above all. Pretend the internet and cell phones didn’t exist, how will you communicate? If you’re interested in learning more, ask me!~

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rjenkins
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Re: All networking info is in this thread

#2 Post by rjenkins »

Hi Rob,

Aren't Class A networks the rare and expensive ones, there are only 126?
There are over a million Class C networks.

Also, I believe only 192.168.x.x is private use in the Class C range, I'm sure I've seen public 192.x.x.x addresses?

There again, it could be me that's trying to confuse me..

Another useful bit of info is that within any subnet range, the lowest .0 address is reserved for the network itself and the highest (typically .255) address is the broadcast address.

Robert.
(Edit, typo - 126 Class A not 125; 128 less 0.x; reserved and 127.x; localhost)
Last edited by rjenkins on Sun Mar 29, 2009 7:58 am, edited 1 time in total.
Robert Jenkins
Presently using a CF-31 Mk5, Toughbook #10 (I think.. too many to keep track of)

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Rob
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Re: All networking info is in this thread

#3 Post by Rob »

rjenkins wrote:Hi Rob,

Aren't Class A networks the rare and expensive ones, there are only 125?
There are over a million Class C networks.

Also, I believe only 192.168.x.x is private use in the Class C range, I'm sure I've seen public 192.x.x.x addresses?

There again, it could be me that's trying to confuse me..

Another useful bit of info is that within any subnet range, the lowest .0 address is reserved for the network itself and the highest (typically .255) address is the broadcast address.

Robert.
"There again, it could be me that's trying to confuse me.." - Yes that is correct :P

There are millions of class A networks, not class C

"Also, I believe only 192.168.x.x is private use in the Class C range" - Thats what I said :P
"I'm sure I've seen public 192.x.x.x addresses?" - no way man these are private, not public

"Another useful bit of info is that within any subnet range, the lowest .0 address is reserved for the network itself and the highest (typically .255) address is the broadcast address." - Yes and I will get into that later
~Rob - Rugged Depot
~Cell: (630)/300-8877~
~Owner - Toughbooktalk~
~Fully rugged Toughbook user since April 18th 2005~
~FZ-55 - Primary Toughbook / Workstation
~AT&T Business 1GB Fiber 1GB/1GB business static line~
~Gamber & Johnson Platinum Partner~

http://www.toughbooktalk.com
http://downloads.toughbooktalk.com/
http://www.rugged575.com - 300' UHF GMRS Radio Repeater


~Emergency preparedness starts with reliable communication systems above all. Pretend the internet and cell phones didn’t exist, how will you communicate? If you’re interested in learning more, ask me!~

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nine
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Re: All networking info is in this thread

#4 Post by nine »

Actually, 192.168.0.0/16 is the private block, the rest of the /8 is public.

Per RFC-1918, the three private blocks are 10/8, 172.16/12 and 192.168/16. There's also the 169.254/16 defined in RFC-3927 as a Link local block, essentially another private network. There are a bunch more reserved address, RFC-3330 has a good summary.

IANA moved away from the old class A,B,and C network assignments a long time ago, and now does classless assignments. For a good discussion of why, and how the CIDR assignments work, see http://en.wikipedia.org/wiki/CIDR.

as an asside, the /x notation means that the first x bits of the address are the network prefix, and the remaining bits are the host. So an (old) class A is an /8, a class B a /16, and a class c a /24

nine, who used to work at a site with a 192.16.?/24 address assignment
nine

Toughbooks, I have a few :)

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