N+ Chapter 5 Flashcards
List of connectivity devices (p. 133)
- NIC
- Hub
- Bridge
- Basic switch
- Basic router
- Basic firewall
- IDS/IPS/HIDS
- Access point
- Wireless range extender
- Contention methods
- DHCP server
- Load balancer
- Proxy server
- Cable modem
- DSL modem
- Repeater
- Voice gateway
- Media converter
- VPN headend
- VOIP phone
- Printer
- Physical access control devices
- Cameras
- HVAC sensors
- IoT
- Refrigerator
- Smart speakers
- Smart thermostats
- Smart doorbells
- Industrial control systems/supervisory control and data acquisition (SCADA)
- Installed in your computer to connect your computer to the internet
- Layer 2 device –> uses MAC address for communication (Data Link layer)
- Provides PHYSICAL, ELECTRICAL, and ELECTRONIC connections to the network media
- Can be an EXPANSION CARD or BUILT-IN INTO THE MOTHERBOARD
***** Common now: built into motherboards - Can provide 10, 100, and 1,000 Mbps
- Ethernet speed increasing with 25, 40, and 100 G
NIC
- LED lights of NIC (usually green), indicating that connection has been established
- Flickers when traffic is being passed back or forth
***** No standard for NIC LEDs
(p. 134)
Link light
Automatically assigns IP addresses to hosts
DHCP
Addressing hosts manually
Static assignment/static IP addressing
What happens if the DHCP server isn’t on the same segment as a DHCP client?
The broadcast won’t be received by the server because BY DEFAULT, routers won’t forward broadcasts
Sending request to one server or destination IP
Unicast
Sending request to multiple servers
Broadcast
True or False: It is possible to have DHCP server on every network segment, but that is not necessary because of the routers forwarding ability
True
Provide IP configuration for hosts on a specific subnet
Can provide the following to DHCP clients:
1. TTL
2. DNS server
3. TFTP server –> especially important for IP phones that need to get a configuration for a TFTP server
Scope options
The amount of time before the IP address and other DHCP information expires on the client (p. 150)
*** Important because it tells you that the DHCP server is no longer handing out IP addresses to hosts
*** Fix: check server settings
Lease time
Used by Windows for name resolution
NetBIOS information
Host always receives the same IP address because of this.
Reservation list/MAC reservation
Why is it called MAC reservation?
Reservation is made on the basis of the router interface Mac address
When to use reservation list?
- You would use this reservation list for routers or servers if they were not statically assigned
- You can use the reservation list for any host on your network as well
What layer is DHCP?
Application layer
Ports for DHCP
67 and 68
What do you need to do if you need to provide addresses from a DHCP server to host that aren’t on the same LAN as a DHCP server?
*** If we don’t do this, the request will just be dropped.
DHCP relay
Configuring router interface to relay or forward the DHCP client requests
DHCP relay
ip helper-address
Ex:
Router#config t
Router(config)#int fa0/0
Router(config-if)#ip helper-address 10.10.10.254
Command that can be used for DHCP relay
Used to forward DHCP broadcasts to where they need to go
Traffic for UDP ports are automatically forwarded to the specified address
Phonebook of the internet
DNS system
FQDN stands for:
Fully Qualified Domain Name
hostname and domain name
FQDN/Fully Qualified Domain Name
name of a device that has a specific IP address
Hostname
The process of finding the IP address for any given hostname
Name resolution
Name resolution ways:
- hosts file –> statically type all the names and the IP addresses of all hosts
- request broadcast on the local network –> Microsoft’s fave
- DNS
- WINS - Windows Internet Naming Service
How are domains arranged on the internet?
Hierarchical structure
Top-level domain is called:
Root
Gives the IP address of a domain or host
A record or address record
In IPV6, A record is called:
Quad-A or AAAA record
If you know the IP address and want to know the host name
Pointer record (PTR)
Translates mail records and points to the mail exchanger for particular hosts
Mail Exchange record (MX record)
Indicates the order in which they should be accessed by other mail delivery systems
Priority code
Other names for CName
canonical name; alias record
Allows hosts to have more than one name
CName
If you want a machine to have the the name FTP so that users can use FTP to access a different portion of the file system as an FTP root, how can accomplish this?
CName record
Ex. p.157
Allow us to update standby servers and have some redundancy in our DNS deployments and distribute the workload across multiple DNS servers
Zone transfers
All devices use a cache system that stores the requests locally for a period of time and this tells the client how long that should be
TTL (Time to Live)
To have the client communicate with multiple DNS servers during the name resolution process
Iterative DNS query
One DNS server will query other DNS servers instead of the client performing all of the operations
Recursive lookup
What layer is DNS?
Application layer
Port for DNS queries
UDP port 53
IP address to name mapping records
PTR records
PTR records reside here, and are used when IP adddress is known but not a name
Reverse lookup zone or table
Stores information about the DNS domain or zone
- How to contact admin
- When was the domain last updated
- How long the server should wait between refreshers
SOA record (Start of Authority)
Hosts register their names with the DNS server as they receive their IP address configuration from the DHCP server
Dynamic assignment/Dynamic DNS
Just connects network segments together
Hub
Segments the network using MAC addresses
Switch/bridge
Segments the network using logical addressing (IP and IPV6)
Router
Breakup collision domains
Switches
Breakup broadcast domains by default
Routers
What layer is the router
Layer 3
Other names for router
Layer 3 switch or multilayer switch
- Keeps a LAN somewhat separated from the Internet, which increases security and filtering control
- Has the tendency to speed up Internet access through caching of recently used web pages
Proxy server
Performed to make sure that the servers are operational
Health checks
Allows incoming connections to be spread out across multiple servers for scalability and resiliency
Publishes a virtual IP address to a domain to receive incoming traffic, then has a pool of real servers that it distributes the contents to
Load balancer
Can decrease the workload of other systems and add functionality that may be present in dedicated devices
VPN concentrators
Let you configure the complete network on a single device and push the configurations out to the Wi-Fi access points
Wireless LAN controllers
Also tunnel the user data back to the controller, which then forwards the traffic onto the LAN.
Access points
Provide accurate date and time information to servers and networking equipment
NTP servers
- A cool temperature
- Ample ventilation
- Proper humidity level
Environmental requirements of infrastructure devices
This device ends and receives information about the network layer
Router
This layer creates a virtual circuit before transmitting between two end stations
Transport
Layer three switch or multi layer switch
Router
This device uses hardware to filter a network
Bridge/switch
Ethernet is defined at these layers
Data link and Physical
This layer supports flow control and sequencing
Transport
This device can measure the distance to a remote network
Router
Logical addressing is used at this layer
Network
Hardware addresses are defined at this layer
Data link (MAC sublayer)
This device creates one big collection domain and one large broadcast domain
Connects all segments of the network together in a star topology ethernet network
Does not segment network
Glorified repeaters
This hardware device will create the most traffic collisions
Hub
This device creates many smaller collision domains, but the network is still one large broadcast domain
Bridge/switch
This device can never run full duplex
Layer 1 device
Hub
This device breaks up collision domains and broadcast domains.
Creates and maintains broadcast domains and connectivity of WAN services
Router
Connects 2 similar network segments together
Main function: keep traffic separated on either side of it, breaking up collision domains; divides busy network into 2 segments
Layer 2 device
Bridge
Connect multiple segments of a network together
Recognizes frames, source and destination MAC addresses, and receiving port
Layer 2 device
Switch
If the switch can’t figure out the location of the frame’s destination…
it will flood the frame out of every port except the one on which the frame port was received
Device that is software-based
Bridges
Device that is hardware-based, multiport bridge
Switch
SOHO stands for:
Small Office Home Office
A device that can function like other devices like firewalls
Router
- IP address is expected to be configured on each interface
- Not enabled by default
- A good network design must be considered before installing it
Router
- IP address is not needed
- Enabled by default
- Very good at autodetecting the speed, duplex, and ethernet cable
type - Plug and play
- All ports are set to duplex by default
- Speed is set to auto
Switch
Ideal speed config for switches
Force 1000 and full duplex
Command to check config
Switch#sh running-config
Command to check speed and duplex options
Switch(config-if)#speed ?
Switch(config-if)#duplex ?
Another term for stand alone firewall
black box
Intermediary network
Screened subnet
DMZ (Demilitarized Zone)
First line of defense for an inter-connected network
Firewall
