routing Flashcards
What standard is Ethernet?
IEEE 802.3
What layer of the OSI model do ethernet frames operate on?
data link
What do the ethernet frames contain?
Source and dest MAC address.
What are sniffers?
Listening to all network traffic even if it isn’t intended for you. This can happen when the NIC runs in promiscuous mode.
What is CSMA/CD?
Carrier sense multiple access /collision detection
What is carrier sense?
computer analyzing wire before sending frame
What is a collision domain?
A group of nodes that can all send data all at the same time, which can definitely cause collision.
What is a hub?
Just a repeater. It reads a signal in and sends it out all the output ports.
What is a switch?
Stores all Mac addresses of devices and stores them on a source address table. Then connects computers with ports.
What is a full duplex switch?
Each port has its own collision domain.
What is a unicast message?
A message just to a single machine
What is a broadcast message?
A message to all machines on a network segment.
What do routers do?
Connect LANs and WLANs, interpret layer 3 (network) and layer 4 (transport). Finds the best paths, reroutes traffic accordingly.
How does routing work?
Layer 2 data gets removed, Ip packet is created and sent through the correct port.
What is a route table?
A database of IPs and subnet masks. Also has Gateway and port currently being used.
What are interior routers?
Connecting multiple LANs on the same domain.
What are border routers?
Connecting domains with their ISP.
What are exterior routers?
Routers the ISP owns or other backbone routers for the internet.
What is NAT?
Network address translation. Basically translates between external IPs and internal IPs.
What are the two types of NAT?
Static and dynamic NAT.
What is a static NAT?
Always give the same mapping to the same device
What is dynamic NAT?
Mapping different devices to different IPs at different times. From a “pool” of all possible IP addresses.
What is PAT?
Port address translation. Dynamically routing one public IP address with multiple ports to multiple private IPs.
What are the three types of ports and the ranges of each?
Well known: 0- 1023
Registered: 1024 - 49151
Dynamic and private: 49152 - 65535
What is port forwarding?
Basically lets someone outside the network connect directly to a machine by specifying the public IP address and the port
What is an ACL?
Access control list. Determines wether or not to drop packet.
