Week 2 - The Network Layer
Why do entries in a local Address Resolution Protocol (ARP) table expire after a short amount of time? A. To keep space in the table B. It will use too much memory C. It only needs to be used one time D. To account for network changes
D. To account for network changes
Service Type field
these eight bits can be used to specify details about quality of service, or QoS technologies
Computer A wants to send some data to computer B. Computer A knows that Computer B is not on its local network, so it sends the packet to the router between Network A and Network B. Based on how many network hops have happened, how much will the TTL field be decremented by?
2
Destination IP Address field
32 bit field of the destination IP address
Source IP Address field
32 bit field of the source IP address
Subnet Masks
32-bit numbers that are normally written out as four octets in decimal
How many octets are in an IPv4 address?
4
Header Length field
4 bit field that declares how long the entire header is which is almost always 20 bytes in IPv4; 20 bytes is also the minimum required length
Protocol field
8 bit field that contains data about what transport layer protocol is being used; TCP and UDP are the most common
How many IP addresses does a class C network have? A. 256 B. 65,536 C. 16,777,216 D. 1
A. 256
How many bits long is a Autonomous System Number (ASN)? A. 32 B. 8 C. 64 D. 4
A. 32
Which number cannot be represented by eight bits of data? A. 436 B. 12 C. 128 D. 232
A. 436
Who is permitted to use non-routable address space? A. Anyone B. The IANA C. It's for testing purposes only D. The IETF
A. Anyone
A typical routing table may contain which of the following? Check all that apply. A. Destination Network B. Total hops C. Destination Address D. TTL
A. Destination Network B. Total hops
An ARP broadcast is sent to the special MAC address? A. FF:FF:FF:FF:FF:FF B. 00:00:00:00:00:00 C. 255.255.255.255 D. 192.168.0.1
A. FF:FF:FF:FF:FF:FF
A subnet ID is calculated via a? A. Subnet Mask B. Demarcation Point C. Router D. Routing Protocol
A. Subnet Mask
In binary 1 + 1 = ? A. 2 B. 10 C. 1 D. 0
B. 10
Please select all of the valid IP addresses: A. 257.70.312.49 B. 192.168.1.1 C. 123.456.123.456 D. 8.8.8.8
B. 192.168.1.1 D. 8.8.8.8
What is the process of taking a large network and splitting it up into many individual and smaller subnetworks called? A. Dynamic Host Configuration Protocol (DHCP) B. Subnetting C. Cloud Computing D. Clustering
B. Subnetting
What information will you find in the 16-bit field in an IP datagram? A. The header length field B. The total length of the datagram it's attached to C. The Internet Protocol version D. The quality of service technologies
B. The total length of the datagram it's attached to
Select examples of routing protocols: A. Hypertext Transfer Protocol B. User Datagram Protocol C. Border Gateway Protocol D. Routing Information Protocol E. Transmission Control Protocol
C. Border Gateway Protocol D. Routing Information Protocol
What does CIDR stand for? A. Classfull Identification Routing B. Classfull Inter-Destination Routing C. Classless Inter-Domain Routing D. Classless Internet Destination Routing
C. Classless Inter-Domain Routing
What is the term for the place one network ends and another begins? A. DMZ B. Subnet C. Demarcation Point D. NAT firewall
C. Demarcation Point
What is the process of taking a single IP datagram and splitting it up into several smaller datagrams called? A. Clustering B. NAT Firewall C. Fragmentation D. Load Balancing
C. Fragmentation
What is the purpose of an ARP response? A. To improve authentication security B. To send an ACK message to the broadcasting computer C. To let a computer broadcasting an ARP message know what MAC address to put into the destination hardware address field D. To prevent a flood of UDP packets
C. To let a computer broadcasting an ARP message know what MAC address to put into the destination hardware address field
Which of the following is a correct form of CIDR notation? A. 192.168.1.0:24 B. 192.168.1.0 + 255.255.255.0 C. 192.168.1.0\24 D. 192.168.1.0/24
D. 192.168.1.0/24
How many bits long is an IP address? A. 64 bits B. 256 bits C. 8 bits D. 32 bits
D. 32 bits
How many octets does a subnet mask have? A. 1 B. 2 C. 3 D. 4
D. 4
Static IP Address
IP address which must be configured on a node manually and are normally reserved for servers and network devices
TTL stands for?
Time to Live
Identification field
a 16-bit number that's used to group messages together when the total amount of data that needs to be sent is larger than what can fit in a single datagram (16 bits or 65,535); every packet with the same ID field is apart of the same transmission
Autonomous System
a collection of networks that all fall under the control of a single network operator
Routing Table
a data table stored in a router that lists the routes to particular network destinations
IP Datagram
a highly structured series of fields that are strictly defined; network layer data packet; payload of the Ethernet frame
Vector
a list in computer science
ARP Table
a list of IP addresses and the MAC addresses associated with them; table entries generally expire after a short amount of time to ensure changes in the network are accounted for
Router
a network device that forwards traffic depending on the destination address of that traffic
Internet Assigned Numbers Authority (IANA)
a non-profit organization that helps manage things like IP address allocation and ASN
Address Resolution Protocol (ARP)
a protocol used to discover the hardware address of a node with a certain IP address
Exterior Gateway Protocol (EGP)
a routing protocol that operates between autonomous systems, which are networks under different administrative control; Border Gateway Protocol (BGP) is the only EGP in widespread use today
Link State Routing Protocol
a routing protocol used in packet-switching networks where each router constructs a map of the connectivity within the network and calculates the best logical paths, which form its routing table; runs algorithms against this data in order to determine the quickest path to update the routing tables; requires more memory
Padding field
a series of zeros used to ensure the header is the correct total size
Network Address Translation (NAT)
a technology that allows computers on non-routable address space to communicate with other devices on the Internet
Time to Live (TTL) field
an 8 bit field that indicates how many router hops a datagram can traverse before it's thrown away
Dynamic IP Address
an IP address assigned by DHCP which are typically reserved for clients
Dynamic Host Configuration Protocol (DHCP)
an automated mechanism to assign IP addresses and IP configuration information over the network
IP Options field
an optional field used to set special characteristics for datagrams primarily used for testing purposes
Encapsulation
bundling data within 1 unit such as the entire IP datagram being only the Ethernet frame payload
Fragmentation Offset field
contains values used by the receiving end to take all the parts of a fragmented packet and put them back together in the correct order
Interface (Routing Tables)
determines which routing interfaces it should forward traffic, matching the destination network, out of
Destination Network (Routing Table)
each network that the router knows about
Version field
first 4 bites of the IP Datagram that indicate what version of IP being used with the most common being IPv4 and IPv6
Total Length field
indicates the total length of the IP datagram it's attached to
Routing Protocols
interior gateway protocols and exterior gateway protocols
Catchall Entry (Routing Table)
matches any IP address that it doesn't have an explicit network listing for
Autonomous System Number (ASN)
numbers assigned to individual autonomous systems
Non-Routable Address Space
ranges of IPs set aside for use by anyone that cannot be routed to
Next Hop (Routing Table)
the IP address of the next router that should receive data intended for the destination networking question or states the network is directly connected and that there aren't ant additional hops needed
Network ID
the first octet of an IP address common to all nodes on the same network or subnet
Subnetting
the process of taking a large network and splitting it up into many individual and smaller subnetworks, or subnets
Fragmentation
the process of taking a single IP datagram and splitting it up into several smaller datagrams
RFC 1918
the public standard that defines public and private IP addresses and outlines non-routable address space
Host ID
the second, third, and fourth octets of an IP address that defines a specific machine in a subnet.
Distance-Vector Routing Protocol
the simplest type of routing protocols; used to determine the best route for data based on the distance to a destination; some distance-vector routing protocols only factor in the number of hops to the destination, while others take into account latency and other network traffic characteristics
Demarcate
to set something off
Total Hops (Routing Table)
total number of hops away from the destination; looks for the quickest route
Class A IP Address
use the first octet as the network ID and the last three octets as the host ID
Class C IP Address
use the first three octets as the network ID and the last octet as the host ID
Class B IP Address
use the first two octets as the network ID and the last two octets as the host ID
Interior Gateway Protocol (IGP)
used by routers to share information within a single autonomous system; Link State Routing Protocols and Distance-Vector Routing Protocols
Flag field
used to indicate if a datagram is allowed to be fragmented or to indicate that the datagram has already been fragmented
Classless Inter-Domain Routing (CIDR)
uses subnet masks to demarcate networks; network ID and subnet ID are combined into one; slash notation
Demarcation Point
where one network or system ends and another one begins
Header Checksum field
a checksum of the contents of an entire IP datagram header
