-: Network services. 2 2
In this section of the course, 3 3
we're going to discuss some network services 4 4
that are testable on the CompTIA Network+ exam. 5 5
For the exam, you must be able to explain the purpose 6 6
of each network service, it's use, 7 7
and some basic configuration information for each one. 8 8
Specifically, we're going to talk about DHCP, DNS, and NTP 9 9
in this section of the course. 10 10
Now, DHCP is the Dynamic Host Configuration Protocol. 11 11
DHCP is a network management protocol 12 12
that is used for internet protocol networks 13 13
for the automatic assignment of IP addresses to devices, 14 14
as well as to providing the subnet mask, default gateway, 15 15
and DNS server for the device to use 16 16
when it connects to the internet. 17 17
We're going to talk more about DHCP 18 18
and its configuration options in a separate video 19 19
to more fully cover DHCP in depth. 20 20
DHCP is going to operate over ports 67 and 68 21 21
using the User Datagram Protocol, known as UDP. 22 22
Next we have DNS, which is the Domain Name System. 23 23
DNS is a protocol that's used to convert domain names 24 24
to IP addresses using a hierarchal 25 25
and decentralized system of naming. 26 26
DNS is a phone book for the internet, essentially. 27 27
So, when you type in diontraining.com into your web browser, 28 28
you don't have to memorize the IP address of my web server. 29 29
Instead, DNS is going to convert it for you. 30 30
DNS is a bit unique in that it operates both 31 31
over UDP and TCP using the exact same port, 32 32
port 53. 33 33
When DNS is conducting a domain name query or lookup, 34 34
it's going to use UDP to accept that request from a client 35 35
and then send the response from that server back. 36 36
But, if DNS is going to be doing a zone transfer 37 37
between two different servers, 38 38
it's going to use TCP for that. 39 39
Now, a zone transfer is the method used by DNS servers 40 40
to share information between themselves 41 41
about which domains they have 42 42
and the associate IP addresses for those domains. 43 43
For this server-to-server communication, 44 44
TCP is going to be used instead of UDP 45 45
because these servers want to verify 46 46
that the information was received by the other server 47 47
and that it was properly received during that transfer. 48 48
Again, we're going to talk more about DNS in a separate video, 49 49
where we could spend more time digging 50 50
into all the different DNS record types and their uses. 51 51
Finally, we're going to talk about NTP 52 52
or the Network Time Protocol. 53 53
NTP is a networking protocol 54 54
that's used for the synchronization of clocks 55 55
between different computer systems 56 56
that communicate over a packet-switched, 57 57
variable-latency data network. 58 58
Now, TCP IP networks are packet-switched networks. 59 59
So, NTP is going to be used for the synchronization of time 60 60
across our IP-connected servers when using TCP. 61 61
NTP is kind of special because it's really old 62 62
and yet, we still use it today. 63 63
In fact, NTP is one of the oldest internet protocols 64 64
that we still use in modern networks. 65 65
NTP data is going to be sent using UDP over port 123. 66 66
We're going to be spending an entire video in this section 67 67
talking all about NTP as well, 68 68
so you can better understand how it operates, 69 69
both from the client and server perspective 70 70
to make sure everyone's using the same time in, 71 71
so you can understand why time is so important. 72 72
So, in this section, 73 73
we're going to be diving into domain one, 74 74
networking fundamentals, 75 75
and we're going to focus only on one objective here. 76 76
Objective 1.6. 77 77
This objective states 78 78
that you have to be able to explain the use 79 79
and purpose of network services. 80 80
All right, let's get started talking 81 81
all about DHCP, DNS, and NTP in this section of the course.