Basics of Networking Flashcards
In simple words, what does the NAT protocol do?
The Network Address Translation protocol is a method of mapping one IP address to another. So it ensures that any external response to traffic coming from a device comes back to the correct locally assigned IP.
Why does the NAT protocol accept connections out and responses back, but does not allow connections in?
Because the local IP address is unknown and a local address shouldn’t be routed across the internet.
What defines the layer 1 of the OSI Model?
The physical layer is how the devices are physically connected.
If a device uses more than one layer, in which one do we classify it?
We classify a device by its greater layer. If a device uses layers 1 and 2, it will be classified as a layer 2 device.
What is the Data Link layer?
It’s the layer responsible to transfer data between adjacent network nodes.
Does the Data Link layer transmit data over different networks?
No, it only traverses a single network.
What does the ARP protocol do?
The Address Resolution Protocol translates an IP address to a MAC address.
Will your MAC address be recorded in the logs of an internet web server you access? Why?
No. ARP traffic is not routed beyond the local network.
Does the first three octets of a MAC address identify the manufacturer?
Yes. The first octets are called the OUI, Organitonally Unique Identifier.
Can a MAC address be spoofed?
Yes. There’s ways to spoof it at a software level.
Can a MAC address be spoofed?
Yes. There’s ways to spoof it at a software level.
What does the Network Layer do?
Transmit data to different networks. Routes packages between different networks.
How does the IP address 192.168.101.42 would be on a network with a netmask of 255.255.255.0?
It would be 192.168.101.0
What are Subnet Masks used for?
They are used to identify the different parts of the IP address. Which bits will refer to the network address.
Which operation can be used on the IP address and subnet mask to determine the network identifier?
A bitwise AND.
What is the advantage in using CIDR?
CIDR allows for much more flexible subdivisions of network space because any number of bits can be used to define the network portion.
What could be happening in the following situation: Computers on your network are being assigned the wrong DNS server IP address and all of them are using DHCP.
Someone has setup another DHCP server. An attacker could setup a rogue DHCP server and take control of the DNS, resulting in attacker controlled responses to all DNS queries.
What is routing?
Is the process of moving packets between networks.
In how many networks can a router be simultaneously connected?
A router can be connected to two or more networks simultaneously.
How do we prevent infinite routing loops?
For each hop the TTL is decremented by 1. When it hits 0, the packet expires in transit.
What is a hop?
Is each router between a source and destination,
At which layer can fragmentation occur? Why?
At layer 3. Because fragmentation is a feature of IPv4, which operates at layer 3.
Why does NAT help with the IPv4 address exhaustion?
Because it’s used to map a public IP address to a single private address. With that, multiple devices can share a single public IP address.
True or false: Your computer has an IP address of 192.168.100.5. When you access www.sans.org, 192.168.100.5 will be recorded in their web server logs.
False. The request will be sent by the router, so the router’s public IP will be stored in the logs. The response will be mapped to the local IP address of the device (192.168.100.5) using the NAT protocol.
