Acknowledgments, sequencing, and flow control are characteristics of which OSI layer?
Options
A. Layer 2
B. Layer 3
C. Layer 4
D. Layer 7
Correct Answer
Layer 4
Explanation
A reliable Transport layer connection uses acknowledgments to make sure all data is transmitted and received reliably. A reliable connection is defined by a virtual circuit that uses acknowledgments, sequencing, and flow control, which are characteristics of the Transport layer (layer 4).
Internetworking problems
Search Results
1. What type of RJ45 UTP cable is used between switches?
Options
A. Straight-through
B. Crossover cable
C. Crossover with a CSU/DSU
D. Crossover with a router in between the two switches
You must be able to take a binary number and convert it into both decimal and hexadecimal. To convert to decimal, just add up the 1s using their values. The values that are turned on with the binary number of
10110111 are
128 + 32 + 16 + 4 + 2 + 1 = 183. To get the hexadecimal equivalent, you need to break the eight binary digits into nibbles (4 bits),
1011 and
0111. By add- ing up these values, you get
11 and
7. In hexadecimal,
11 is
B, so the answer is
0xB7.
3. Which fields are contained within an IEEE Ethernet frame header?
Source and destination MAC address
Source and destination network address
Source and destination MAC address and source and destination network address
An Ethernet frame has source and destination MAC addresses, an Ether-Type field to identify the Network layer protocol, the data, and the FCS field that holds the answer to the CRC.
4. How does a host on an Ethernet LAN know when to transmit after a collision has occurred?
In a CSMA/CD collision domain, multiple stations can successfully transmit data simultaneously.
In a CSMA/CD collision domain, stations must wait until the media is not in use before transmitting.
You can improve the CSMA/CD network by adding more hubs.
After a collision, the station that detected the collision has first priority to resend the lost data.
After a collision, all stations run a random backoff algorithm. When the backoff delay period has expired, all stations have equal priority to transmit data.
Once transmitting stations on an Ethernet segment hear a collision, they send an extended jam signal to ensure that all stations recognize the collision. After the jamming is complete, each sender waits a predetermined amount of time, plus a random time. After both timers expire, they are free to transmit, but they must make sure the media is clear before transmitting and that they all have equal priority.
5. Segmentation of a data stream happens at which layer of the OSI model?
Hubs cannot run full-duplex Ethernet. Full duplex must be used on a point-to-point connection between two devices capable of running full duplex. Switches and hosts can run full duplex between each other, but a hub can never run full duplex.
7. Which two statements describe the IP address 10.16.3.65/23?
The subnet address is 10.16.3.0 255.255.254.0.
The lowest host address in the subnet is 10.16.2.1 255.255.254.0.
The last valid host address in the subnet is 10.16.2.254 255.255.254.0.
The broadcast address of the subnet is 10.16.3.255 255.255.254.0.
The mask 255.255.254.0 (/23) used with a Class A address means that there are 15 subnet bits and 9 host bits. The block size in the third octet is 2 (256 - 254). So this makes the subnets in the interesting octet 0, 2, 4, 6, etc., all the way to 254. The host 10.16.3.65 is in the 2.0 subnet. The next subnet is 4.0, so the broadcast address for the 2.0 subnet is 3.255. The valid host addresses are 2.1 through 3.254.
8. Using the following illustration, what would be the IP address of E0 if you were using the eighth subnet? The network ID is 192.168.10.0/28 and you need to use the last available IP address in the range. The zero subnet should not be considered valid for this question.
A /28 is a 255.255.255.240 mask. Let's count to the ninth subnet (we need to find the broadcast address of the eighth subnet, so we need to count to the ninth subnet). Starting at 16 (remember, the question stated that we will not use subnet zero, so we start at 16, not 0), 16, 32, 48, 64, 80, 96, 112, 128, 144. The eighth subnet is 128 and the next subnet is 144, so our broadcast address of the 128 subnet is 143. This makes the host range 129-142. 142 is the last valid host.
9. The network address of 172.16.0.0/19 provides how many subnets and hosts?
A CIDR address of /19 is 255.255.224.0. This is a Class B address, so that is only 3 subnet bits, but it provides 13 host bits, or 8 subnets, each with 8,190 hosts.
10. Your router has the following IP address on Ethernet0: 172.16.2.1/23. Which of the following can be valid host IDs on the LAN interface attached to the router?
The router's IP address on the E0 interface is 172.16.2.1/23, which is 255.255.254.0. This makes the third octet a block size of 2. The router's interface is in the 2.0 subnet, and the broadcast address is 3.255 because the next subnet is 4.0. The valid host range is 2.1 through 3.254. The router is using the first valid host address in the range.