After 19 years of being in the industry, I decided to take some refresher course, I’m hoping to learning something new. Today I decided to learn or revisit network terminology.
Network Terminology
Host: A host is any device that is connected to a network. Typically a host will use 1 ip address. Here are some examples of host on most network: computers, servers, printers, canner, ip phone, ip camera. Hmmmm.. this lead me to a question… is a router consider a host? Honestly, I’m not even sure. Technically, it does take up 1 ip address, so I guess in a way, I would consider it a host. I’m not 100% sure though, but in the interest of time, I’m moving on. There are other devices on the network that is important, yet it does not take up an ip address, so it is not consider a host. Example of non host devices on network can be modems, hubs, and some network switches. Typically unmanaged switches does not take up an ip, so it’s not consider a host. Managed switches on the other hand, does take up ip address, so it would be consider a host, at least in my book.
IP Address: An ip address is a number that identifies a host. In a network, each host have it’s own ip address. If you have 2 host of the same ip address, it would be consider a conflict and those two host will most likely not work properly. Ip address can be version 4 or version 6. In version 4 ip address, it can be internal or public. Internal ip is assign a number that only accessible via it’s direct neighbor or host on the same lan. External ip address is typically a number that is assign to you by the isp (internet service provider). A router, typically can use a public ip and an internal ip. This is how you can multiple host on a network can share 1 internet connection. Ip address is on the layer 3 of our network model. A good example of an internal (local) ip address would be 192.168.1.1. A good example of an external ip address would be 8.8.8.8 (google public dns). You can’t access 192.168.1.1 from anywhere in the world, but you should be able to access 8.8.8.8 from anywhere as so long as you are not being blocked by some kind of security configuration.
LAN: A LAN (Local Area Network) consists of multiple host on the same network. A good example would be you have your server, 3 computers, and 2 printers in your office in Austin, then that would be consider a LAN. You can have multiple LAN on one network. A good example would be you have your normal day to day data on LAN 1 (typically call VLAN), then you can have all your VOIP phones on LAN 2 (VLAN2). You can tag all your traffic on VLAN2 to have priority over your normal data traffic. If you have a remote office with the exact same setup in Dallas, then that would be consider another LAN. You can actually tie two LANs together via VPN, Private Point to Point Ethernet Network, MPLS, and SD WAN.
