Lesson 5: Objectives Flashcards
WAN interface is usually what?
How are they connected?
Point-to-point meaning there are only two devices connected to the media (unlike ethernet)
Ethernet connections are made using what?
(Hardware)
2
NIC’s and Switches.
WAN Interface is typically made by what kind of hardware?
Digital Modem
What are the 5 links to an internet connection>
- Hosts attached to a switch port or connected to the access point use ethernet and wi-fi to communicate
- SOHO wireless router implements all functions for local network and internet connectivity
- digital modem adapter in the router connects to an external line
- External line connects to the ISP’s PoP (Point of Presence)
- The ISP’s network forwards traffic over the internet
What establishes the physical connection to the WAN interface?
Modem
When interconnecting networks, there must be a way to identify each network and forwarding data between them. What performs this function?
the router
When interconnecting networks, there must be a way to identify each network and forwarding data between them. What is used as identification?
IP (Internet Protocol)
What “flavors” of DSL are there?
(Digital Subscriber Line)
(3)
S(symmetric)
A(Symmetric)
V(ery High Bit Rate)
What else is POTS known as?
local loop
last mile
ADSL provides what speed downlink and what speed uplink?
(Asymmetric DSL)
fast / slow not numbers
fast downlink
slow uplink
What kind of cabling is used for the core of the PSTN?
(Public Switched Telephone Network)
Fiber Optic Cable is dominant
What speed uplink and downlink does symmetric DSL offer?
fast / slow, not numeric
the same uplink and downlink speeds.
Is asymmetric or symmetric DSL more useful for businesses?
Symmetric, where more data is transferred upstream than with normal internet use.
On a standalone DSL modem, what kind of port on the modem connects to the phone point?
RJ-11 WAN port
What kind of port / interface is used on DSL modems to connect the modem to the router?
RJ-45
With DSL, what must be installed to each phone socket to separate voice and data signals?
Filter / Splitter
A CATV network is often described as what?
HFC hybrid fiber coax
HFC combines what?
(Hybrid Fiber Coax)
(Hardware)
(2)
fiber optic core network with copper coaxial cable links
What is the major obstacle to providing internet access that can perform like a LAN?
Bandwidth in the last mile
copper wiring infrastructure is often low-grade
What are the 5 connections on cable modem
- Cable Modem –> Local Router –> RJ-45
- AP’s Network w/short coax –> Threaded F-Type Connector
- Coax links all premises in a street with CMTS
- Forwards data traffic w/fiber backbone to ISP’s PoP
- To the Internet
AP Access Point
CMTS Cable Modem Termination System
PoP Point of Presence
The cable modem is interfaced to the local router with what kind of port?
RJ-45
CATV / HFC can also be described as what?
Cable Access TV / Hybrid Fiber Coax
Broadband cable
cable
DOCSIS v3 allows the use of what to achieve higher bandwidth?
multiplexed channels
What benefit does LEO (Low Earth Orbit) Satellites have over traditional satellites?
Lower RTT / Latency time
What type of DSL achieves the highest bit rates?
VDSL
Very High Bit Rate DSL
What kind of cable / connector is a cable modem connected to the Access Providers network with?
Short segment of coax
terminated using threaded F-type connectors
What does the ONT do? (Optical Network Terminal)
Converts the fiber optic signal to an electrical one.
In a PON (Passive Optical Network), what kind of cable is run, and from what point to what point?
a single fiber cable is run from an OLT (Optical Line Terminal) to a splitter.
In a PON (Passive Optical Network), where does the splitter direct traffic to?
Splitter directs each subscribers traffic over a shorter length of fiber to an ONT (Optical Network Terminal)
Where is the ONT? (Optical Network Terminal)
installed at the customer’s premises.
What is the ONT connected to? Using What? (Optical Network Terminal)
Connected to the customer’s router using an RJ-45 Copper Wire Patch Cord
What is one drawback of satellites placed in a high geostationary orbit?
increased latency
because the signal must travel over thousands of miles more than terrestrial connections, giving a greater delay
Where are the orbital satellites located
Over the equator
(Pointing south for the northern hemisphere for satellites and pointing north for the southern hemisphere)
How is satellite internet connected?
(3)
- ISP installs a VSAT (Very small aperture terminal) satellite dish antenna at the customers premises
- ISP aligns the VSAT with the orbital Satellite.
- Antenna is connected via coaxial cable to DVB-S Modem (Digital Video Broadcast Satellite)
What is the drawback of LEO (Low Earth Orbit) Satellites?
LEO (Low Earth Orbit) Satellites move relative to Earth so the customers antenna must have a motor to periodically realign with the satellite.
Antenna must have a clear view of the whole sky
WISP (Wireless Internet Service Provider) uses what kind of wireless technology?
ground-based long-range fixed access wireless technology
WISP (Wireless Internet Service Provider) installs and maintains a directional antenna to work as a bridge between the customer’s network and the ISP.
might use Wi-Fi type networking or proprietary equipment
Do WISP’s (Wireless Internet Service Provider) use licensed or unlicensed frequency bands?
Both
what is the disadvantages of fixed access wireless (Wisp (Wireless Internet Service Provider))
(2)
the actual unobstructed line of sight between the two antennas can be difficult to maintain.
If the ISP uses unlicensed frequencies, there are risks of interference from other wireless networks and devices
All types of microwave radio link can be adversely affected by what?
(3)
snow
rain
high winds
With 3G Cellular Wireless, how does the radio make a connection?
to the nearest base station.
With 3G Cellular Wireless, the area served by ease base station is referred to as what?
a “cell”
With 3G Cellular Wireless, what is the effective range of each cell?
5 miles
8 km
though signals can be obstructed by building materials.
With 3G Cellular Wireless, there are two competing formats
- GSM (Global System for Mobile Communication)
- CDMA (Code Division Multiple Access)
With 3G Cellular Wireless, what is the difference between GSM (Global System for Mobile communication) and CDMA? (Code Division Multiple Access)
- GSM: Phones allow subscribers to use SIM cards to unlock handset with chosen network provider
- CDMA: handset is directly managed by the provider and there is no removable SIM
(Global System for Mobile communication)
(Subscriber Identity Module)
(Code Division Multiple Access)
With 3G Cellular Wireless, UMTS (Universal Mobile Telecommunications Service) is used on what format?
GSM Global System for Mobile communication
H/H+ / HSPA (High Speed Packet Access) is used with what kind of cellular network?
3G
With 3G Cellular Wireless, EV-DO (Evolution Data Optimized) is used on what format phone?
GSM VS CDMA
CDMA Cell Division Multiple Access
Is 4G LTE supported by GSM or CDMA network providers?
both
5G uses what?
different spectrum bands from low to medium/high.
low bands = greater range and penetrating power
high bands = close range and cannot penetrate walls and windows
What makes rolling out 5G wireless complex?
Rather than a single large antenna serving a wide area, 5G requires many smaller antennas to form an array that can take advantage of multipath and beamforming to overcome propagation limits of the spectrum.
5G technology is referred to as what?
Massive MIMO Multiple Input Multiple Output
What serves as both the protocol needed to connect to the internet and the system interface?
Device
Router
What forwards a MAC (hardware) address?
a switch
A MAC address identifies what?
a hardware port
what forwards packets to the internet using IP addresses?
routers
What does a LAN router do? (Local Area Network)
(2)
- divides a single physical network into multiple logical subnetworks
- each logical network becomes a separate broadcast domain.
An IP address contains what information? (2)
- the identity of both the network and
- a single host within that network.
What kind of interfaces does a LAN router typically have?
ethernet only
what kind of interface does a WAN router have? (2)
- ethernet interface for local network
- digital modem interface for the WAN
The role of filtering allowed and denied hosts and protocols is performed by what?
a network firewall
What is a security benefit of a LAN router?
traffic passing from one logical network to another can be subject to filtering rules.
what does a WAN or border Router do?
forwards traffic to and from the internet or over a private WAN link.
Each entry in a network firewalls ACL (Access Control List) (rules) lists what? (3)
- the source and/or destination network address
- protocol types and
- whether or not to allow or block traffic that matches that rule
basic firewall rules is referred to as what?
network access control list
Most networks use what kind of protocol Suite?
TCP / IP
(Transmission Control Protocol / Internet Protocol)
The function of each TCP / IP protocol is better understood by diving network functions into layers.
What are the 4 network layers?
Application
Transport
Internet
Link/Network Interface
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Name some examples of the Application Layer: (14)
- DHCP
- DNS
- FTP
- HTTP/HTTPS
- SMTP
- IMAP
- POP3
- SSH
- RDP
- Telnet
- LDAP
- SNMP
- Syslog
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Name 2 examples of the Transport layer:
- TCP
- UDP
The function of each TCP / IP protocol is better understood by diving network functions into layers
Name an example of the internet layer
IP
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Name 2 examples of the Link / Network Interface Layer
- Ethernet
- Wi-Fi
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Link / Network Interface Layer: What is this layer responsible for?
Putting frames onto the physical network.
The function of each TCP / IP protocol is better understood by diving network functions into layers.
What Layer would DSL work under?
The Link / Network Interface Layer
The function of each TCP / IP protocol is better understood by diving network functions into layers.
What layer would cable modems work at?
The Link / Network Interface Layer
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Link / Network Interface Layer: What protocols are used on this layer?
Does not contain TCP/IP Protocols
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Link / Network Interface Layer: Where do communications take place on this layer?
Only at the local level and not between networks.
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Internet Layer: What does the IP provide?
packet addressing and routing within a network of networks.
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Internet Layer: For data to be sent from one network to another, it must be forwarded by what?
an intermediate system (Router)
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Internet Layer: IP provides what?
Best effort delivery that’s unreliable and connectionless. a packet might be lost, delivered out of sequence, duplicated, or delayed.
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Transport Layer: What does the transport layer do?
determines how each host manages multiple connections for different application layer protocols at the same time.
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Internet Layer: What does the internet layer deal with
Addressing
The function of each TCP / IP protocol is better understood by dividing network functions into layers.
Regarding the Transport Layer: TCP provides what kind of packet forwarding?
Transmission Control Protocol
guarantees connection-oriented forwarding of packets.
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Transport Layer: What does TCP do that makes it more reliable than UDP
Transmission Control Protocol
User Datagram Protocol
TCP can identify and recover from lost or out of order packets.
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Transport Layer: what kind of applications tend to us UDP
User Datagram Protocol
time-sensitive applications such as speech or video.
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Transport Layer: is TCP or UDP faster?
UDP
because it doesn’t need to send extra information to establish reliable connections.
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Application Layer: what is the purpose of the application layer protocols?
they perform high-level functions beyond addressing and sending data. Used to configure and manage network hosts and to operate services.
What does the IP in the TCP / IP protocol provide?
network and host addressing and packet forwarding between networks.
The function of each TCP / IP protocol is better understood by diving network functions into layers.
Regarding the Transport Layer: How reliable is UDP Forwarding?
User Datagram Protocol
unreliable and connectionless forwarding.
How many bits is an IPv4 address?
32 bits long.
In an IPv4 address: what two pieces of information are encoded within the same value?
The network ID
The host ID
How can an IPv4 address be arranged?
into 4 groups of 8 bits (one byte) eg.
11000000101010000000000000000001
11000000 10101000 00000000 00000001
IPv4 addresses are made easier to use by putting them in dotted decimal notation. how is this done?
by converting each octet into a decimal value
In an IPv4 address, what identifies a host within a particular IP network?
host ID
In an IPv4 address what identifies the network common to all hosts on the same IP network?
Network ID
When a host attempts to send a packet via IPv4, the protocol compares what?
the source and destination IP address in the packet against the sending host’s subnet mask.
if the masked portions of the source and destination IP address match, then the destination interface is assumed to be on the same IP network or subnet.
On Ethernet, the host would use what to identify the MAC address associated with the destination IP address (In IPv4 forwarding)
Protocol
address resolution protocol (ARP)
IPv4 forwarding, If the masked portion does not match the source and destination IP:
the host assumes that the packet must be routed to another IP network. It would be forwarded to the a router rather than trying to deliver it locally.
Public IP Addresses are permitted to do what?
Packets with public addresses are permitted to be forwarded over the internet.
The default gateway configured to most hosts must be what?
in the same IP network as the host.
Packets with private IP addresses should be what?
blocked at internet gateways or forwarded using some type of translation mechanism
Public IP addresses are allocated to who by whom?
Customer Networks by
ISP’s
There are 3 ranges of private IPv4 addresses that aren’t allowed to route traffic over the public internet. These addresses are confined to what?
Private LAN’s
What range is the Class A private address IPv4 Range:
10.0.0.0 to 10.255.255.255
What range is the Class B private address IPv4 Range:
172.16.0.0 to 172.31.255.255
What range is the Class C private address IPv4 Range:
192.168.0.0 to 192.168.255.255
IPv4 Class A What is the Dotted Decimal Mask and the Network Prefix?
Specific number
255.0.0.0
/8
IPv4 Class B What is the Dotted Decimal Mask and the Network Prefix?
255.255.0.0
/16
Since private IP addresses can’t access the internet directly, some mechanism must be used to allow it to forward packets. Internet access can be facilitated for hosts using private addressing in what two ways:
- NAT: through a router configured with a single or block of valid public addresses, using the NAT to convert between the private and public addresses
- Through a proxy server that fulfills requests for internet resources on behalf of clients
IPv4 Class C What is the Dotted Decimal Mask and the Network Prefix?
255.255.255.0
/24
What are the minimum requirements for a host to be configured with to communicate on an IPv4 Network?
- IP address
- Subnet Mask
In the IPv4 address 192.168.0.100 which number is the network ID?
192.168.0
In the IPv4 address 192.168.0.100, which number is the host ID?
.100
What is the default gateway parameter?
The IPv4 address of a router. This is the IP address to which packets destined for a remote network should be sent by default.
Failure to enter a gateway would result in what?
This would limit the host to communication on the local network only.
Typically the primary DNS server address would be configured as what?
the same as the gateway address.
The router would be configured to forward DNS queries to a secure resolver.
Often, two DNS server addresses are specified for what reason?
redundancy: A preferred DNS server and an alternate
What do DNS servers provide?
resolution of host and domain names to their IP addresses and are essential for locating resources on the internet.
How would a static IP address be configured?
manually by the computer admin configuring the IP information on each computer and updating the settings if the host was moved to a different IP network or subnet.
Static IP addresses are typically only assigned to what kind of systems?
systems with a dedicated functionality such as router interfaces or application servers that require a fixed IP address.
DHCP servers would configure what 4 settings with the computer?
IP address
Subnet Mask
Default Gateway
DNS server addresses
APIPA is also called what?
link-local address
What IP range is an APIPA address set to ?
169.254.x.y
When a host is using an APIPA address, who can it contact?
other hosts on the same network using APIPA addresses, but cannot reach other networks or communicate with hosts that have managed to obtain a valid DHCP lease.
The Router’s public Interface IP address is determined how?
by the ISP
How many bits is an IPv6 address?
128
When shortening IPv6 addresses, what can be ignored?
a double byte contains leading zeros, the zeros can be ignored
ie:
0db8 = db8
0db8:0000:0000:0abc = db8::abc
In IPv6 Addresses, one hex digit can represent what kind of value?
a 4-bit binary value
Instead of a gateway, IPv6 addresses use a protocol called what?
ND
Neighbor Discovery
What are the two main parts of an IPv6 address?
- Network ID (64 bits)
- Interface ID (64 bits)
What is a global IPv6 address?
one that is unique on the internet.
In IPv6, what is used to determine whether two addresses belong to the same IP network?
the 64-bit network ID, the length of any given network prefix
In IPv6 addresses, why is there no need for a subnet mask?
because the network and host portions are a fixed size.
In hex notations, global addresses start with what?
2 or a 3
What is a link-local address
IPv6 address that is used on the local segment to communicate with neighbor hosts.
In hex notation, link-local addresses start with what?
fe80
ND = what in IPv4
Neighbor Discover = ARP in
At the link layer, Ethernet allows hosts to send one another frames of data using MAC addresses. What would these frames typically be transporting?
IP packets
Of the 4 layers of network functions, which layer would the IP provide addressing and routing functionality for a network of networks?
The internet layer
Of the 4 layers of network functions, which layer identifies each type of network application?
The transport layer
The transport layer (of network functions) serves to identify each type of network application. How is this accomplished?
It assigns each application a port number between 0 and 65,535
What port does HTTP web browsing applications use
Port 80
What is port 80?
HTTP web browsing applications
Email transmission services uses what port?
25
What is used by port 25
SMTP
Email transmission service
If a host is transmitting multiple HTTP and email segments at the same time, which port would be used?
The ports would be multiplexed using the port numbers onto the same network link.
How does IP transmit streams of application data?
as a series of packets
TCP is described as what?
a connection-oriented protocol
TCP protocols are called connection-oriented protocols (which overcomes the lack of IP reliability) with what 5 functions?
- Establishes a connection between the sender and the recipient using a handshake sequence of SYN, SYN/ACK, and ACK packets
- Assigns each packet a sequence number so that it can be tracked
- Allows the receiver to acknowledge (ACK) that a packet has been received
- Allows the receiver to send a negative acknowledgement (NACK) to force retransmission of a missing or damaged packet
- Allows the graceful termination of a session using a FIN handshake
What is the main drawback to TCP protocols?
the connection information requires multiple header fields.
This can add 20 bytes or more to the size of each packet
Name 2 application protocols that must use TCP
- HTTP/HTTPS
- SSH
What is HTTP / HTTPS used for?
delivers web pages and other resources. The secure version uses encryption to authenticate the server and protect the information being transmitted.
A single missing packet would cause this process to fail entirely.
What does SSH protocol do?
Used to access the command-line interface of a computer from across the network. it uses encryption to authenticate the server and user and protect the information that’s being transmitted.
Using UDP for video or audio, how would missing packets manifest?
as glitches in the video or audio
Name two protocols that use UDP
- DHCP (Dynamic Host Configuration Protocol)
- TFTP (Trivial File Transfer Protocol)
What does DHCP do?
(Dynamic Host Configuration Protocol)
Used by clients to request IP configuration information from a server. It uses broadcast transmissions, which aren’t supported by TCP, so it must use UDP.
Protocol is simple, so if response packet isn’t received, the client just restarts the process and tries again repeatedly until timing out.
What does the TFTP protocol do?
(Trivial File Transfer Protocol)
Protocol is typically used by a network device to obtain a configuration file. The application protocol uses its own acknowledgement messaging so it doesn’t require TCP
What Port does the following Protocol Use: FTP Data Connection (File Transfer Protocol)
20
What Port does the following Protocol Use: FTP Control Connection (File Transfer Protocol)
21
What Port does the following Protocol Use: SSH (Secure SHell)
22
What Port does the following Protocol Use: Telnet
23
What Port does the following Protocol Use: SMTP (Simple Mail Transfer Protocol)
25
What Port does the following Protocol Use: DNS (Domain Name System)
53
What Port does the following Protocol Use: DHCP Server (Dynamic Host Configuration Protocol)
67
What Port does the following Protocol Use: DHCP Client (Dynamic Host Configuration Protocol)
68
What Port does the following Protocol Use: HTTP (HyperText Transfer Protocol)
80
What Port does the following Protocol Use: POP ( Post Office Protocol)
110
What Port does the following Protocol Use: NetBIOS over TCP/IP
137-139
What Port does the following Protocol Use: IMAP (Internet Mail Access Protocol)
143
What Port does the following Protocol Use: SNMP (Simple Network Management Protocol)
161
What Port does the following Protocol Use: HTTPS (HyperText Transfer Protocol Secure)
443
What Port does the following Protocol Use: SNMP Trap Operation (Simple Network Management Protocol)
162
Does the following protocol use TCP or UDP: DHCP (Dynamic Host Configuration Protocol)
UDP
What Port does the following Protocol Use: SMB (Server Message Block)
445
What Port does the following Protocol Use: LDAP (Lightweight Directory Access Protocol)
389
Does the following protocol use TCP or UDP: SMTP (Simple Mail Transfer Protocol)
TCP
Does the following protocol use TCP or UDP: HTTPS (HyperText Transfer Protocol Secure)
TCP
What Port does the following Protocol Use: RDP (Remote Desktop Protocol)
3389
Does the following protocol use TCP or UDP: SMTP (Simple Mail Transfer Protocol)
TCP
Does the following protocol use TCP or UDP: HTTP (HyperText Transfer Protocol)
TCP
Does the following protocol use TCP or UDP: FTP (File Transfer Protocol)
TCP
Does the following protocol use TCP or UDP: SMB (Server Message Block)
TCP
Does the following protocol use TCP or UDP: DNS (Domain Name System)
TCP & UDP
Does the following protocol use TCP or UDP: LDAP (Lightweight Directory Access Protocol)
TCP
Does the following protocol use TCP or UDP: SSH (Secure SHell)
TCP
Does the following protocol use TCP or UDP: Telnet
TCP
Does the following protocol use TCP or UDP: POP (Post Office Protocol)
TCP
Does the following protocol use TCP or UDP: RDP (Remote Desktop Protocol)
TCP
Does the following protocol use TCP or UDP: NetBIOS
UDP & TCP
Does the following protocol use TCP or UDP: IMAP (Internet Mail Access Protocol)
TCP
Does the following protocol use TCP or UDP: SNMP (Simple Network Management Protocol)
UDP
Does the following protocol use TCP or UDP: NETBIOS (Over TCP/IP)
UDP
What is the purpose of the following protocol: FTP Data Connection (File Transfer Protocol)
Make files available for download across a network (Data connection port)
Does the following protocol use TCP or UDP: FTP Control Connection (File Transfer Protocol)
TCP
What is the purpose of the following protocol: DNS (Domain Name System)
Facilitate identification of hosts by name alongside IP addressing
What is the purpose of the following protocol: Telnet
Makes an unsecure connection to the command line interface of a server
What is the purpose of the following protocol: DHCP Client (Dynamic Host Configuration Protocol)
Request a dynamic IP address configuration from a server
What is the purpose of the following protocol: IMAP (Internet Mail Access Protocol)
Read and manage mail messages on a server mailbox
What is the purpose of the following protocol: HTTP (HyperText Transfer Protocol)
Provision unsecure websites and web services
What is the purpose of the following protocol: DHCP Server (Dynamic Host Configuration Protocol)
Provision an IP address configuration to clients
What is the purpose of the following protocol: SSH (Secure SHell)
Makes a secure connection to the command line interface of a server
What is the purpose of the following protocol: POP (Post Office Protocol)
Retrieve email messages from a server mailbox
What is the purpose of the following protocol: SNMP (Simple Network Management Protocol)
Query Status information from network devices
What is the purpose of the following protocol: SNMP Trap Operation (Simple Network Management Protocol)
Report status information to a management server
What is the purpose of the following protocol: LDAP (Lightweight Directory Access Protocol)
Query information about network users and resources
What is the purpose of the following protocol: HTTPS (HyperText Transfer Protocol Secure)
Provision secure websites and services
What is the purpose of the following protocol: SMB (Server Message Block)
Implement windows compatible file and printer sharing services on a local network
What is SMB (Server Message Block) also sometimes referred to?
CIFS (Common Internet File System)
What is the purpose of the following protocol: RDP (Remote Desktop Protocol)
Make a secure connection to the graphical desktop of a computer
What is DHCP scope?
(Dynamic Host Configuration Protocol)
The range of addresses that a DHCP server can offer to client hosts in a particular subnet.
What should a DHCP Scope exclude?
Dynamic Host Configuration Protocol
Should exclude any addresses that have been configured statically.
When a DHCP client initializes, what packet does it broadcast to find a DHCP server?
DHCPDISCOVER
When a DHCP server responds to a client, what is the packet name it sends back containing the address and other configuration information?
(Such as the default gateway and DNS server addresses)
(Dynamic Host Configuration Protocol)
DHCPOFFER
When DHCP server sends the DHCPOFFER packet, the client may choose to accept the offer using what packet that is also broadcast onto the network?
DHCPREQUEST
When the DHCP client sends the DHCPREQUEST packet to the DHCP server, assuming the offer is still available, the server will respond with what packet?
DHCPACK
Once a DHCP client accepts the DHCPACK, what does the client do?
Broadcasts the ARP message to check that the address is unused.
If so, it will start to use the address and options,
If not, it declines the address and requests a new one.
What is a DHCP Lease?
Dynamic Host Configuration Protocol
Address configuration assigned by a DHCP server tp a client for a limited period of time.
What is a DHCP reservation?
Dynamic Host Configuration Protocol
It’s often useful for IP addresses to be known and to remain the same. While this can be done with a static IP, that can be difficult to maintain.
A DHCP reservation allows you to reserve a particular IP address for each device. the DHCP server is configured with a list of the MAC addresses of hosts that should receive the same IP address.
nut.widget.example
nut is what?
widget.example is what?
nut = host name
widget.example = domain suffix
At the top of the DNS hierarchy is what and how is it represented?
root
represented by the null label which is just a period (.)
What is a FQDN?
Fully Qualified Domain Name
Host names are unique to the local network.
FQDN are language based unique identifiers that are unique to the internet and can be combined with a domain name and suffix.
In the DNS hierarchy, what are the 13 root identities?
How are they represented?
A–M
What do the 13 root identities in the DNS hierarchy represent?
1500 individual servers each providing identical information from the root zone to DNS resolvers all over the world
What are the 6 layers of the DNS hierarchy?
- Root
- TLD (Top Level Domain)
- Country Code Subdomain
- Domain
- Subdomain
- Resource Records
In the DNS hierarchy name 3 examples of how TLD are represented?
(Top Level Domain)
- uk
- net
- com
In the DNS hierarchy name 1 example of how Country Code Subdomains are represented
co
In the DNS hierarchy name 2 examples of how domains are represented
515web
515support
In the DNS hierarchy give one example of how subdomains are represented
corp
In the DNS hierarchy name 2 examples of how resource records are represented
www
pc
What is an (A) Address record?
(Referring to DNS Records)
used to resolve a host name to an IPv4 Address.
What is an (AAAA) address record?
(Referring to DNS record types?)
resolves a host name to an IPv6 address
What is a MX Resource Record?
used to identify an email server for the domain so that other servers can send messages to it.
In a typical network, multiple servers are installed to provide redundancy, and each one will be represented by what?
(DNS Records)
MX Record Number
Mail Exchanger
Every MX number is given what?
Mail Exchanger
a preference value with the lowest numbered entry preferred.
The host name identified in a MX record must have an associated what?
Mail Exchanger
A or AAAA record
What is a TXT record?
used to store any free form text that may be needed to support other network services.
A single domain name may have many TXT records, but they are most commonly used to verify email services and block the transmission of spoofed and unwanted messages / spam
(DNS Spam Management Records)
What is a SPF?
Sender Policy Framework?
DNS record identifying hosts authorized to send mail for the domain
Who publishes an SPF and what does it use?
a DNS by an organization hosting email services publishes them
Uses a TXT resource record.
How many SPF can be had for each domain?
Sender Policy Framework
one per domain
What does the SPF issued to a domain indicate?
Sender Policy Framework
identifies the hosts authorized to send email from that domain.
can also indicate what to do with mail from servers not on that list.
DomainKeys Identified Mail (DKIM) does what?
Uses cryptographic authentication mechanism for mail utilizing a public key published as a DNS record
Validates the source server for a given message
DomainKeys Identified Mail (DKIM) Can replace or supplement what?
SPF Sender Policy Framework
How is DomainKeys Identified Mail (DKIM) configured?
the organization uploads a public encryption key as a TXT record in the DNS server.
What does Domain-Based Message Authentication, Reporting, and Conformance (DMARC) do?
It’s framework to ensure that SPF and DKIM are being utilized effectively. (Utilizing a policy published as a DNS record)
Specifies a more robust policy mechanism for senders to Specify how DMARC authentication failures should be treated, plus mechanisms for recipients to report DMARC authentication failures to the sender
Sender Policy Framework
DomainKeys Identified Mail
How is a Domain-Based Message Authentication, Reporting, and Conformance (DMARC) Policy published?
As a DNS TXT record
All hosts connected to the same unmanaged switch are said to be in the same what?
broadcast domain
VLAN’s are what?
Virtual LAN
Logical network segment comprising a broadcast domain established using a feature of managed switches to assign each port a VLAN ID.
Even if hosts on 2 VLANs may be physically connected to the same switch, local traffic is isolated to each VLAN, so they must use a router to communicate
VLAN’s Mitigate what problem?
Virtual LAN
Placing hundreds or thousands of hosts in the same broadcast domain reduces performance
What is the simplest way to assign a node to a VLAN?
Configure the port interface on the switch with a VLAN ID in the range of 2 - 4094
Can hosts placed in separate VLAN’s communicate with one another directly?
No.
Each VLAN must be configured with what? (3)
-It’s own subnet address
-IP address range
-It’s own DHCP and DNS services
How do VLAN’s function from a security standpoint?
They are each represented as a separate zone. Traffic passing between VLAN’s can easily be filtered and monitored to ensure it meets security policies.
VPN enables hosts to do what?
connect to the LAN without being physically installed at the site.
In a remote access VPN, what would be located between the VPN client and the Local Network?
3
-Remote Access Screened Subnet
-VPN Gateway
-Router / Firewall
In remote access VPN network, what devices would be located on the Local Network?
Router / Firewall
LAN Servers
In a VPN remote access network, where is the VPN encryption tunnel?
With the VPN client over the internet between the VPN client and the remote access screened subnet.
What does FTP Protocol do?
Make files available for download across a network (Control Connection Port)
