WEBVTT 0:00:09.560000 --> 0:00:13.520000 Hello, welcome to this video part of the CCNA exam assessment where we're 0:00:13.520000 --> 0:00:19.740000 going to be testing you on comparing TCP against UDP. 0:00:19.740000 --> 0:00:23.980000 Question number one. 0:00:23.980000 --> 0:00:32.940000 At which layer of the OSI reference model does UDP reside? 0:00:32.940000 --> 0:00:38.380000 And that would be the transport layer, answer D. 0:00:38.380000 --> 0:00:53.300000 Question two. Which of the following features is supported by UDP? 0:00:53.300000 --> 0:00:58.260000 Answer is C. Multiplexing using ports. 0:00:58.260000 --> 0:01:03.040000 All of the other ones are either supported by TCP or not supported by 0:01:03.040000 --> 0:01:06.580000 either of them at all. 0:01:06.580000 --> 0:01:16.300000 Question three. Which of the following is a benefit of designing an application 0:01:16.300000 --> 0:01:24.940000 to utilize UDP instead of TCP? 0:01:24.940000 --> 0:01:30.020000 And that would be lower overhead because UDP header is much, much smaller 0:01:30.020000 --> 0:01:34.040000 than TCP and doesn't have a lot of the synchronization and other benefits 0:01:34.040000 --> 0:01:39.780000 of UDP. Of TCP, there's a lot lower overhead when application is using 0:01:39.780000 --> 0:01:42.580000 UDP instead of TCP. 0:01:42.580000 --> 0:01:54.980000 Question four. Which of the following applications typically rely on TCP 0:01:54.980000 --> 0:02:02.660000 rather than UDP? 0:02:02.660000 --> 0:02:05.500000 Now would be answer C. 0:02:05.500000 --> 0:02:11.020000 Hypertext data transfer, otherwise known as HTTP. 0:02:11.020000 --> 0:02:17.200000 Voice over IP, video over IP, and domain name resolution all rely on UDP, 0:02:17.200000 --> 0:02:21.720000 which makes those incorrect. 0:02:21.720000 --> 0:02:31.320000 Question five. Which of the following items taken together constitute 0:02:31.320000 --> 0:02:34.740000 a TCP or UDP socket? 0:02:34.740000 --> 0:02:37.280000 Select three answers. 0:02:37.280000 --> 0:02:46.100000 And those three things would be an IP address, a transport protocol identifier, 0:02:46.100000 --> 0:02:50.220000 for example within the IP header it has to identify whether it's UDP or 0:02:50.220000 --> 0:02:55.920000 TCP, and a port number, a UDP or TCP port number. 0:02:55.920000 --> 0:03:02.480000 All of those taken together are what we call a TCP or UDP socket. 0:03:02.480000 --> 0:03:14.860000 Question six. In the chart below, fill in the missing or blank cells. 0:03:14.860000 --> 0:03:20.280000 So for example, if the port number cell is blank, fill that in. 0:03:20.280000 --> 0:03:30.040000 If the protocol or application cell is blank, fill that in. 0:03:30.040000 --> 0:03:41.440000 And here are your answers for those various cells that were missing information. 0:03:41.440000 --> 0:03:52.200000 Question seven. How many steps are involved in establishing a TCP connection 0:03:52.200000 --> 0:04:00.780000 between hosts? And hopefully you answered three. 0:04:00.780000 --> 0:04:07.000000 It's called a three way handshake for TCP. 0:04:07.000000 --> 0:04:16.600000 Question eight. Given the following TCP connection that's being established 0:04:16.600000 --> 0:04:22.020000 between two hosts, fill in the yellow boxes with the TCP flags that are 0:04:22.020000 --> 0:04:25.220000 used in each step of the process. 0:04:25.220000 --> 0:04:28.860000 Notice here that the connection is being initiated on the left from the 0:04:28.860000 --> 0:04:32.880000 PC going to the right, which is the server. 0:04:32.880000 --> 0:04:39.540000 So here's your answer. 0:04:39.540000 --> 0:04:46.160000 So the TCP device that's initiating sends the TCP SIN flag, which is short 0:04:46.160000 --> 0:04:51.460000 for synchronization, trying to synchronize a connection to the destination. 0:04:51.460000 --> 0:04:56.380000 The destination responds back with an acknowledgement and its own synchronization, 0:04:56.380000 --> 0:04:58.840000 its own SIN flag. 0:04:58.840000 --> 0:05:01.460000 And then we finish up with the ACK flag. 0:05:01.460000 --> 0:05:05.040000 So that is your TCP three way handshake making use of those particular 0:05:05.040000 --> 0:05:14.500000 flags. Question nine. 0:05:14.500000 --> 0:05:20.940000 A TCP receiver has received 5,000 bytes of data, after which it sends 0:05:20.940000 --> 0:05:28.400000 a TCP ACK. That TCP ACK contains a sequence value of 5,001. 0:05:28.400000 --> 0:05:33.260000 This process of acknowledging data by referencing the next byte that is 0:05:33.260000 --> 0:05:41.340000 expected is called Hopefully you answered B. 0:05:41.340000 --> 0:05:46.400000 That is called forward acknowledgement. 0:05:46.400000 --> 0:05:55.700000 Question ten. And this will be our final question in this section. 0:05:55.700000 --> 0:06:01.840000 What is the name of the TCP mechanism by which a TCP sender knows how