Applied Networking: MCQ 2
Which layer allows the DHCP Server to distribute IP settings to DHCP Clients on the same LAN/vLAN?
Application Layer (7th Layer)
What does it mean to have a dynamic configuration?
Assign address for a limited time, lease, and then return address to the pool for re-use.
What does APIPA stand for?
Automatic Private IP Addressing
True or False: Delivery is 100% guaranteed when moving datagrams (packets) from the source device to the destination device.
False: Delivery is not guaranteed, packets can get lost, duplicated, delayed, or delivered out of order
True or False: Not every device needs to have a link-local address
False: Each device MUST have a link-local address
True or False: Classful addressing is very flexible and adaptive
False: It is very rigid and strict
True or False: The Data (Payload) changes from source to destination.
False: The Data (Payload) does not actually change from source to destination.
True or False: IPv6 extensively uses broadcast addresses and rarely utilizes multicasts.
False: There are no broadcasts with IPv6 and they extensively use multicast addresses.
What does it mean to have a static configuration?
Fixed IP address - Some systems need fixed or static IP addresses ( servers, routers, etc)
What does layer 2 work with?
Frames
True or False: DHCP is "Stateful" as it has a pool of addresses to allocate out
True
True or False: It is possible for router to give out DNS information when SLAAC is used.
True
True or False: Routers block broadcasts
True
True or False: Within IPv6, in the absence of a DHCP server, devices on a LAN can automatically obtain IP addresses themselves and start using the network.
True
True or False: APIPA service checks regularly for DHCP server.
True Every 5 minutes in fact.
Fill in the blank: Router's Link-local is ____________ created
statically
Why is SLAAC known as "stateless"?
"Stateless" because it begins from a "dead start" with no information (or "start") at all for the host to work with
What is the lowest possible device address?
*.*.*.0
What is the highest possible device address?
*.*.*.255
What are the 3 main private IP addresses within this area?
- 10.*.*.* - 172.16.*.* - 192.168.*.*
What are some improvements of the IPv6 from the IPv4?
- Better Security: IPsec is built-in and part of the IPv6 protocol - New IPv6 header format: Non-essential fields in the IPv4 header were removed making it more efficient. - Extensibility: IPv6 was designed to be easily extendable by adding extension headers after the IPv6 header.
What details does the DHCPOffer include?
- IP Address being offered - Client's MAC Address - Subnet mask - Lease duration - IP Address of the server making the offer
How does APIPA configure itself?
- IP address range is 169.254.0.0 to 169.254.255.254 - Subnet mask is 255.255.0.0 - No default gateway address (communication limited to within LAN)
What are the three major types of IPv6 addresses you can have?
- Link Local Address: Local scope within LAN, APIPA address (FE80::) - Unique Local Address: Internal LAN scope, Private IP address (FC00::/8, FD00::/8) - Global Unicast Address: Global scope, Internet, Public IP address (2000::/3, 2001::/3)
What are some examples of IPv4 addresses we will NEVER see on the internet?
- Private Internet addresses (unique local): EX 10.*.*.*, 172.16.*.*, 192.168.*.* - Loopback (localhost) addresses: EX 127.*.*.*/8 - APIPA addresses (local link): EX 169.254.*.* - Broadcast Address: 255.255.255.255
What are the five Regional Internet Registries?
- RIPE (Europe) - ARIN (North America) - LACNIC (South America) - APNIC (Asia Pacific) - AFRINIC (Africa)
Why do there need to be DHCP broadcast flags?
- Some clients CANNOT receive unicast IP data until configured with IP address (Bit = 1) - Some clients CAN receive unicast IP data before being fully configured with IP address (Bit = 0)
What are the different interpretations of 0.0.0.0?
- This device: All IP addresses on the local machine. - DHCP: Client source IP address. - Routing Tables: Default Route, used by routing tables
What IP address does a device assign if it does not support APIPA?
0.0.0.0
What is the minimum payload length?
1 byte
What are the classifications of IP addresses?
1. Class A/8 - Subnet Mask: 255.0.0.0 - Example: 10.*.*.* 2. Class B/16 - Subnet Mask: 255.255.0.0 - Example: 172.16.*.* 3. Class C/24 - Subnet Mask: 255.255.255.0 - Example: 192.168.10.* 4. Class D - No subnet mask - Range: 224.0.0.0 - 239.255.255.255 5. Class E
What are the four basic phases of DHCP operations?
1. Discover 2. Offer 3. Request 4. Acknowledgement
How can a client detect IP address conflicts?
1. Once client receives an ACK from DHCP server, they send an ARP request to that IP address (expecting to get no response) 2. If a reply is received, this indicates that some device is already using that IP address 3. The client sends a DHCPDecline message to the DHCP server. 4. The client begins a new request process Reminder: Client CANNOT Ping because it is a Layer 3 protocol and the client doesn't have an IP address
What are ways a device can be configured with an IPv6 address?
1. Static / Manually Configured 2. Stateful DHCPv6 3. Stateless Address Autoconfiguration (SLAAC) - DNS
Explain the process of TTL
1. TTL is initially set by the device sending the datagram. ( 128 and 255) 2. Each router that receives the datagram subtracts 1 from TTL. 3. If the count remains greater than 0, the router forwards the packet, otherwise router discards packets.
How does the DHCP Server prevent address conflicts?
1. The DHCP Server attempts to Ping the IP address being offered. 2. If a response is received, that indicates the IP address is already in use. 3. The server allocates next available IP address and reissues the Ping
How long is an IPv6 address?
128 bits
What is ATU's public IP address?
193.1.57.1 / 21
What is the minimum header length required in a packet?
20 bytes
What is the IP broadcast address?
255.255.255.255 In addition, device addresses of all 1's is also a directed broadcast address - Ex. 192.168.0.255/24 - Ex. 172.16.255.255/16
What is the maximum datagram size?
2^16 = 65,536 bytes
What is the maximum header length allowed in a packet?
60 bytes
How many bits long is the IPv6's Interface ID?
64 bits
How many bits long is the IPv6's Network address?
64 bits
What is the maximum payload length?
65,536 bytes
What is the Router Advertisement?
A message that is used in IPv6 networks to convey information from routers to devices on the local link. Routers periodically send these messages to announce their presence and to provide essential configuration parameters to devices on the network.
What is a Router Solicitation?
A message used in IPv6 networks to request the presence and configuration information of routers on the network. Within DAD, this system asks IPv6 routers on the link about the global unicast prefix to use.
What are the two addresses that the IP Address indicates?
Both the LAN address and the Device address
What does CIDR stand for?
Classless Inter-Domain Routing
What is used to reduce the wastage of IP addresses with Classful Addressing?
Classless Inter-Domain Routing (CIDR)
What does the phase "request" refer to within the process of DORA?
Clients may receive many DHCPOffers from different servers. The client chooses which offer to accept and broadcasts a DHCPREQUEST to indicate which DHCP Server the client accepts an offer from. - Once the DHCP servers receive this REQUEST, they withdraw any offers that they might have made to the client and release the reserved IP address - Any number of DHCP servers can respond to a DHCPOFFER, but the client can only accept one offer per NIC.
What does the phase "offer" refer to within the process of DORA?
DHCP Server receives a DHCP Discover request, reserves an IP Address for the client, and responds with an IP Address offer. (DHCPOffer) - DHCPOffer is sent either as a broadcast or unicast
What is APIPA?
DHCP clients can automatically self-configure when no DHCP server is available. - The client searches for DHCP server, but if none is available, they will automatically configure itself. - The client uses this IP address until DHCP server becomes available
Fill in the blank: Layer 3 is concerned with moving _____________ / ____________ from Source device to Destination device.
Datagrams / Packets
What does layer 3 work with?
Datagrams / packets
What does DAD stand for?
Duplicate Address Detection
What does DHCP stand for?
Dynamic Host Configuration Protocol
What type of addresses does Layer 3 use?
IP addresses - IPv4 (32 bits / 4 bytes) - IPv6 (128 bits / 16 bytes)
What IP settings can the DHCP assign or apply to a system?
IP addresses, subnet mask, IP gateway, DNS address, and network names.
Where does IPv6 get their network addresses from?
ISP
How does fragmentation work with datagrams?
If the datagram is carried by Ethernet, the max frame data size is 1500 bytes. So, to transport the datagram, it will need to be split into smaller packets, each with its own header. The new header is almost a duplicate of the original header except for offset, flags, and length fields.
What does IANA stand for?
Internet Assigned Numbers Authority
What is the header length?
It contains control information, such as source and destination addresses, error-checking codes, and other metadata required for the proper delivery of the packet.
What is Classless Inter-Domain Routing (CIDR)?
It is designed to keep the internet from running out of IP addresses and making routing more efficient
How is the Interface ID of IPv6 generated?
It is either a random number or EUI-64 (Extended Unique Identifier)
What is the Extended Unique Identifier (EUI-64) made up of?
It is made up of the 48-bit MAC address and a 16-bit 0xFFFE
What is the lowest device address reserved for?
It is reserved for the actual LAN itself
What does NAT do?
It is used to translate public addresses into private addresses or visa versa.
What is the purpose of TTL or hops?
It limits undeliverable packets from circulating forever and clogging up the network.
What does an address with a subnet mask of 255.255.255.255 mean and where is it most commonly used?
It means the network has only 1 single device and it is mostly used in Routing Tables.
What are the advantages of having a 64-bit number randomly generated for IPv6 addresses?
It prevents or limits tracking of the host address location and user activities.
Within this address, what is the /24 referring to? 192.168.0.10 /24
It refers to the length of the network address. In this instance, the network address takes up 24 bits of the IP address, leaving 8 bits for the device address.
What is the payload length?
It refers to the size of the data or information carried in a packet, excluding the packet headers.
What addresses does layer 2 use?
MAC Address
What does MTU stand for?
Maximum Transmission Unit
What does NAT stand for?
Network Address Translation
What are the Regional Internet Registries (RIRs)?
Organizations responsible for the allocation and registration of Internet number resources like IP addresses.
What type of address is the Destination IP address?
Public IP address
What does RIR stand for?
Regional Internet Registries
What device changes the Source IP address from private to public?
Router
What is the device of Layer 3?
Router
What does layer 4 work with?
Segments
What does SLAAC stand for?
Stateless Address Autoconfiguration
Within this subnet mask, what do the 0s refer to? 255.255.255.0 11111111.11111111.11111111.00000000
The 0s refer to the Device address. In this instance, the LAN address will take up 24 bits of the entire IP address, leaving only 8 bits to identify the Device address.
Within this subnet mask, what do the 1s refer to? 255.255.255.0 11111111.11111111.11111111.00000000
The 1s refer to the LAN address. In this instance, the LAN address will take up 24 bits of the entire IP address, leaving only 8 bits to identify the Device address.
What does the phase "discover" refer to within the process of DORA?
The client broadcasts a request looking for IP configuration data and fills in as many fields as are known. - Client can request its last-known IP address (i.e. Preferred) - Router can be configured (IP Helper-Address) to forward DHCP requests to a DHCP server on a different LAN or VLAN
What is the Subnet mask?
The dividing line between the network address and the device address.
What is the highest device address reserved for?
The highest device address is all ones, and it is reserved for the broadcast address.
What does the phase "acknowledgement" refer to within the process of DORA?
The server receives a DHCPREQUEST and sends back ACK to the client. - ACK includes the IP address being offered, Subnet mask, lease duration, and other network-specific information
What are APIPA addresses classified as? Why?
They are classified as a link local addresses since they are only valid within the network the devices are connected to. - This network can temporarily function as a LAN for those devices that have APIPA, but these devices have no gateway address
What device uses multicast addresses?
They are used by routers - EIGRP updates use 224.0.0.10 - OSPF routers listen to 224.0.0.5 - RIPv2 uses 224.0.0.9
What does the router use to translate public addresses to private addresses, or visa versa?
They use NAT to translate the two different types of addresses
What is the Loopback (Localhost) address?
This address is used to test network applications. - 127.x.x.x/8 - The most common address is 127.0.0.1
What is the Internet Assigned Numbers Authority (IANA)?
This authority allocates Public IPv4 addresses by assigning IP addresses in large / 8 blocks to the five Regional Internet Registries. (4.2B Public IP addresses)
What are Class D addresses used for?
This class is multicast addresses where data is destined for a group of devices. - There are no device addresses within the Class D address space since all devices within a group share the group's IP address.
What is a DHCP broadcast flag?
This is the bit number set by the client, telling the server how to respond. Bit = 1: The client expects the server to respond using Broadcast Bit = 0: The client expects the server to respond using Unicast
What does SLAAC do?
This system is used when a device autoconfigures itself with a link-local address FE80::
What does TTL stand for?
Time to live
Fill in the blank: Layer 2 is concerned with moving Frames from one device to another device within the same _____________.
VLAN
What does DAD do?
When a device is configured to use a specific IPv6 address, this system confirms that no other device in the same network is already using that address to avoid conflicts. It checks the local network for any identical IP addresses to ensure it's not already in use.
