1.3 Flashcards
what is access point:
It’s the wireless network device inside the network.
Whats a MAC address:
It’s the Ethernet Media Access Control Address or the unique physical address of a network adapter.
How does the MAC address display?
it is 48 bits or 6 bytes and is shown in hexadecimal.
OUI stands for what?
Organizationally Unique Identifier.
MAC address 2 parts:
- OUI
2. Network Interface Controller-Specific
What is a Half-Duplex?
when a device cannot send and receive data at the same time, that device is half duplex.
What is Full-duplex
when a device can send and receive data at the same time, that device is Full-duplex.
what are some examples of half and full duplex devices:
all LAN hubs are half-duplex and switches are full-duplex unless its connected to other half-duplex devices.
How does a half-duplex device work?
It receives traffic on one interface and repeats it out to other interfaces.
T/F) in half-duplex devices, you can have two or more devices communicating at the same time.
False, if more than one device is communicating, we will have collisions.
Whats the other name for half-duplex:
CSMA/CD
(CS: Carrier Sense
MA: Multiple Access
CD: Collision Detect)
T/F) Half-duplex Ethernet is still being used to this day.
False. Not used any longer.
Explain how CSMA/CD work?
- First the device listens for an opening.
- Then it sends a frame of data (whenever it can, no queue)
- If a collision happens, then it will send a jam signal to let everyone know a collision happened, then it waits a random amount of time and resend the data.
What are CSMA/CA function characterization?
In this half-duplex, there is no collision detection since its not possible but it uses Collision Avoidance and RTS/CTS (ready to send, clear to send)
and it solves the hidden node problem.
What does a switch do?
- Forward or drop frames
- Gather a constantly updating list of MAC addresses.
- Maintain a loop-free environment using STP
Whats STP:
Spanning Tree Protocol
How does a switch learn the MACs?
A switch examines the incoming traffic. Then it adds the unknown MAC addresses to the MAC address table
Why does a switch floods an unknown MACs?
When a switch doesnt have the MAC address in the table or is in doubt, the switch sends the frame to everyone. this process is called flooding.
What does ARP stand for:
Address Resolution Protocol
What does an ARP do:
Determines a MAC address based in an IP address.
What do we use to view the local ARP table?
arp -a
T/F) Collision domain is difficult to be found these days.
True
How is a collision domain removed?
By adding a switch to a network and creating a full-duplex network.
What is a broadcast domain used for?
To send a message to everyone on the network.
how far would a broadcast go?
It pass by a bridge or a switch but it stops at the router.
What is a collision domain:
Is in a network of half-duplex devices when two or more devices try to communicate in that network at the same time.
What is a Unicast:
It’s a one on one communication and info exchange between 2 devices
what are some examples of unicast:
web surfing and file transferring
What is a broadcast:
When a device send info to everyone on a network at once.
What are some examples of broadcast:
Routing updates and APR requests
T/F) broadcasting is used in IPv6.
False. broadcasting can be used in IPv4 but not IPv6 and instead multicast is used.
What is multicast:
It is delivery of information from one device to specific interested devices.
What are some example of multicast:
Multimedia delivery and stock exchange
What is the issue with multicast?
It is very specialized and difficult to scale across large networks.
what does PDU stand for?
Protocol Data Unit
What is a PDU:
a unit of transmission (a different group of data at different OSI layers.
What are TCP and UDP PDU called?
TCP segment and UDP datagram.
What determines the size of the PDU?
MTU, Maximum Transmission Unit
What does MTU do?
Gives us the maximum IP packet to transmit.
What are the issues with fragmentation:
- Slows things down
2. It is difficult to know the MTU all the way through the path
How often do we configure MTU:
usually once based on the network infrastructure and they dont change often.
what do we use for troubleshooting the MTU:
by using ping
What is a LAN made of:
It’s a group of devices in the same broadcast domain.
What is a VLAN:
it’s the virtual local area network or a group of devices in the same broadcast domain separated logically instead of physically.
What is a VLAN trunk?
When two switches are connected using only one physical connection between switches but it is able to transmit multiple VLANs over that trunk.
What does ISL stand for?
Inter-switch Link
What is the standard for trunking?
It used to be ISL but now everyone uses the 802.1q standard.
how long are the VLAN IDs?
12 bits long and can have 4094 VLANs but 0 and 4094 are reserved VLAN numbers.
How can a loop be created between 2 switches?
By using 2 cables to connect 2 switches
whats the problem with a loop and how can it be solved?
It can take down a network. By using IEEE standard 802.1D to prevent loops in a bridged (switched) networks.
What states does a STP port have?
- blocking
- listening
- learning
- forwarding
- disabled
what does RSTP (802.1w) stand for?
Rapid Spanning Tree Protocol (802.1w)
what are the basic interface configurations:
- Speed and duplex
2. IP address management
What are a switch VLANs configurations:
- VLAN assignment
- Trunking
- Tagged and untagged VLANs
What are tagged and un-tagged VLANs:
A non-tagged frame is on the default VLAN (also called the native VLAN) but trunk ports will tag the outgoing frames and remove the tag on incoming frames.
What does DMZ stand for?
Demilitarized Zone
What is DMZ used for?
It’s an additional layer of security between the internet and clients.
what does PoE stand for?
Power over Ethernet
What are some examples of uses of PoE?
Phones, cameras, wireless access points
What is a midspan?
in-line power injector which helps add power to an Ethernet cable when the switch doesnt have the option.
what are the difference in PoE and POE+?
- PoE has up 15.4 watts DC power while the POE+ has 25.5 watts DC power.
- PoE has a maximum current of 350 mA but the POE+ has the current of 600mA.
What does SPAN stand for:
Switch Port Analyzer (also called port mirroring)
What is port mirroring?
its an interface configuration on a switch. When a switch sends a copy of the data to a monitoring device or an analyzer like an IPS and also send the data to the destination.
What is routing?
It’s sending IP packets across the network.
What is static routing?
thats when user is in control and administratively define the routes.
what are advantages of static routing?
- Easy to use in smaller networks.
- No overhead from routing protocols (CPU, memory, bandwidth)
- Easy to configure on sub networks.
- More secure
What are the disadvantages of static routing?
- difficult to admin on larger networks.
- No automatic method to prevent routing loops
- if there is a network change, you have to manually update the routes.
- no automatic routing if an outrage occurs
What is Dynamic routing?
When Routers automatically send routes to other routers.
what are dynamic routing advantages?
- No manual route calculations or management
- New routes are populated automatically
- very scalable
what are dynamic routing disadvantages?
- Some router overhead required (CPU, memory, bandwidth)
2. Requires some initial configuration to work properly
What is a default route?
It’s a route when no other route matches.
What kind of routing does a remote site use?
Default route
Whats the advantage of default route?
- It can significantly simplify the routing process
2. It works in conjunction with all other routing methods.
What is subnet mask?
It is used by the local workstation to determine what subnet it’s on.
What is an IP combined of?
a network ID and a host ID
where is IPv4 in an OSI layer?
layer 3, Network
How many bits are IPv4 and IPv6?
IPv4 is a 32 bits and IPv6 is a 128 bit
What is an AS?
Autonomous System, a group of IP routes under common control.
Whats an IGP?
Interior Gateway Protocol
what are some famous IPv4 dynamic routing protocols?
- OSPFv2 (Open Shortest Path First)
- RIPv2 (Routing Information Protocol version 2)
- EIGRP (Enhanced Interior Gateway Routing Protocol)
What are some famous IPv6 dynamic routing protocols?
- OSPFv2
- EIGRP for IPv6
- RIPing (RIP next generation)
EGP stands for what? and what is it used for?
Exterior Gateway Protocol. It is used to route between autonomous systems
What protocol is used in EGP?
BGP (Border Gateway Protocol)
Whats a dual stack:
It’s when we run both IPv4 and IPv6 at the same time which means interfaces will be assigned multiple address types.
what is tunneling?
As an alternative to dual-stack routing, tunneling can be used to deliver IPv6 packets across the IPv4 Internet.
what kinds of tunneling exist?
- 6to4 addressing which doesn’t require relay routers.
2. 4in6 tunneling which tunnels IPv4 traffic on an IPv6 network
What is IP protocol 41 and what is it used for?
It’s a transition technology which is used in 6to4 adressing.
T/F) 6to4 addressing doesnt support NAT (Network address translation).
True
What is Teredo/Miredo?
A way to use tunnel IPv6 through NATed IPv4 which doesnt need a specific IPv6 router but its only temporary.
What does NPD stand for?
Neighbor Discovery Protocol
T/F) NDP requires broadcast.
False. It operates using multicast.
What does SLAAC stand for?
Stateless Address Auto configuration
What is NDP used for in an IPv6?
- discover other devices on the network for multi casting
- SLAAC (used for devices automatically configure themselves with IP addresses without having access to DHCP)
- DAD (No duplicate IPs are being used in the network.)
- Discover routers
What does SLAAC stand for?
Stateless Address Auto-Configuration
What does DAD stand for?
Duplicated Address Detection
What do RS and RA stand for and what are they used for?
Router Solicitation and Router advertisement. NDP uses them to find a router.
whats used in IPv6 to find MAC address of a device?
Since there is no ARP in IPv6, we use NS and NA.
Whats another name for packet shaping?
Traffic shaping
What is traffic/packet shaping used for?
For prioritization of applications
How does packet shaping work?
- Control with bandwidth usage or data rates
2. Set important applications to have higher priorities than other apps.
What does QoS stand for?
Quality of Service
What is Quality of Service?
It describes the process of controlling traffic flows
What does CoS stand for?
Class of Service
What are some standards used in QoS?
- CoS
- DiffServ
- DSCP
What are some characterizations of CoS?
- OSI layer 2 (happens between switches)
- Ethernet frame header in an 802.1Q trunk
- Usually applied in the intranet
What does DiffServ stand for?
Differentiated Services
What are some characterizations of DiffServ?
- OSI layer 3 (Inside of Routers and Firewalls)
- QoS bits are enabled in the IPv4 header
- Bits are set external to the application
- Routers apply the QoS
What does DSCP stand for?
Differentiated Services Code Point
What devices use NAT?
Routers
What is port forwarding?
It allows someone on the outside to gain access to the devices that you might have on the inside of your network (web server, gaming server, security system).
What are other names for port forwarding?
Destination NAT or Static NAT
What is an access control list and how does it work?
It’s a packet filtering used to allow or deny traffic
What does ACL stand for?
Access Control List
T/F) Most Firewalls do not include an Implicit deny and users need to add them manually.
False. Most firewalls include a deny at the bottom even if users didnt put one.
What is circuit switching?
It’s a circuit established between endpoints before data passes (like a phone) but nobody else can use the circuit when it’s idle.
What are some other names for circuit switch network?
- POTS (Plain old telephone service
- PSTN (Public Switched telephone network.
- T1 / E1/ T3 / E3
- ISDN
What is packet switching?
Packet switching is where we’re grouping data into packets and sending it across a network (like Voice, data, video over a network)
What are some packet switching devices?
- SONET, ATM
- DSL
- Frame relay
- MPLS
- Cable Modem
- Satellite
- Wireless
What does SDN stand for?
Software Defined Networking
What are some characterizations of SDN?
- Directly programmable
- Agile
- Central managed
- Programmatically configured
- Open Standard/ vendor neutral
What is Distributed switching?
It removes the physical segmentation, but if a VM moves, the network doesn’t change.
