IP Flashcards
True/False - A device on one subnet cannot communicate with another device on a different subnet without the help of a router
True
True/False - Subnetting is transparent to the rest of the internet
True
Define subnetting
The process of dividing a network into smaller sized networks
How many hosts are possible on a Class B network
( 2 ^ 16 ) - 2
How many hosts are possible on a Class A network
(2 ^ 24 ) - 2
How many hosts are possible on a Class C network
( 2 ^ 8 ) - 2
What is the purpose of the special IP address 0.0.0.0
Only used in a local network for a src ip until DHCP gives an IP
What is the purpose of the special IP address 255.255.255.255
Limited Broadcast - only for a dst ip in a local network
What are the characteristics of the special IP address type, Network Address
Host ID is all 0’s, cant be used to address to a device
What are the characteristics of the special IP address type, Direct Broadcast
Net ID is specified, host portion is all 1’s, allows broadcast to a different network
How would a special IP address for a specific host on a network look
network id is all 0’s, host id is specified
What is the loopback address and what is its purpose
127.x.x.x , doesnt leave local interface
What are the private IP ranges
10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168. 0. 0 - 192.168.255.255
Describe a subnet mask in terms of the 32 bit sequence
A 32 bit sequence that contains a 1 in every network/subnet portion bit and a 0 in every host portion bit
True/False - All devices including hosts and routers that are located on the same network/subnet must have the same subnet mask
True
True/False - Devices on different subnets may have the same subnet mask
True
True/False - To find the network address, take the IP address and BIT AND it with the subnet mask
True
True/False - IP is a connectionless, unreliable, best-effort service
True
True/False - Routers in the internet ignore the protocol field
True
True/False - IP just checks the header for errors, not the payload
True
True/False - To get the size of the payload take the Total Len and subtract the Hdr Len
True
True/False - Maximum Transmission Unit (MTU) is the Largest Payload a frame can handle
True
True/False - Internet routers treat each fragment as an independent packet
True
True/False - The last fragment must be a multple of 8
False
True/False - Both end-systems and any internet router can fragment a packet
True
True/False - if the rx’er doesnt get all the set of fragments it will drop all the the fragments
True
True/False - All devices including hosts and routers that are attached to the same network must have the same network id portion
True
Describe the NAT/PAT process
- The host creates a packet with its private src IP and its dst IP
- The host creates a frame with its src MAC and dst MAC of local router
- The local router processes the frame and looks at the packet, it sees a private IP as src and replaces the private src ip with the routers public ip
- The local router gets the src port from the payload and maps it to a selected different port in the NAT table. It changes the src port in the payload
- The local router puts an entry in the NAT table with the private IP of the sending host
- When the response comes back the local router finds the port mapping in the nat table to find out which devices to send to
- the local router replaces the dst IP with the original hosts private src IP
True/False - Home routers have higher layer functions, internet routers are strictly layer 3
True
What are the characteristics of a Class A Network
0-127, First bit 0, Net ID: 7 bits (2^7 Networks), Host ID: 24 bits (2^24 Hosts)
What are the characteristics of a Class B Network
128-191, First bits 10, Net ID: 14 bits (2^14 Networks), Host ID: 16 bits (2^16 Hosts)
What are the characteristics of a Class C Network
192-223, First bits 110, Net ID: 21 bits (2^21 Networks), Host ID: 8 bits (2^8 hosts)
True/False - When you BIT AND your own IP with your own subnet mask you get your own network ID
True
True/False - When you BIT AND another host IP with your own subnet mask you get the other host network ID
False
True/False - /31 can represent a point-to-point link
True
What is the block format
a.b.c.d/n
What is the size of a block
The number of ip addresses in the block, 2^32-n
What is the number of addressable devices in a block
2^32-n - 2
True/False - In the case of multiple matches in the routing table the router will choose the longest prefix match
True
What is the DV (Bellman-Ford) Formula
Dx(y) = min{c(x,v) +dv(y)}
