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L E S S O N P L A N #65
Per.
Name:
CLASS: Networking
DATE: Tuesday April 20th, 2010
TOPIC: TCP/IP
AIM: How does DNS Work?
NOTE:
1) At the end of the period, leave your computer on the desktop screen, put the keyboard on top of the monitor and push in your chair.
H.W. # 65:
1) Why was classless routing created?
2) How else can you access a website aside from its domain name?
3) What is name resolution?
DO NOW:
Go to http://public.pacbell.net/dedicated/cidr.html. Read about CIDR.
What is CIDR?
PROCEDURE:
Write the AIM and DO NOW.
Get students working!
Take attendance.
Go Over HW
Collect HW
Go over the Do Now
Assignment #1:
To access a computer on the Internet, you could refer to the IP address of that computer. For example, open up your web browser and go
to the IP address 216.239.51.99 by typing http://216.239.51.99. Whose computer is this?
Alternately, you can take the IP address, in binary form (all 32 bits together) and convert that into a decimal value, then type that decimal
value after the http://
For example, the IP address 1.0.0.1 in binary looks like 00000001 00000000 00000000 00000001
Using place values for power of 2, we have
1(2 24 )  1(2 0 ) = 16777216 + 1 = 16777217
Instead of doing this by hand, you could use a program like bosncalc.exe and select Decimal IP from the menu; we can then convert
from dotted decimal IP to full decimal IP or vice versa.
Use the program to convert Google’s IP of 216.239.51.99 into full decimal and use that after http:// to go to Google’s site.
If a filter (such as the one that filters our Internet traffic) is not configured to also check for full decimal address, you can sometimes
bypass the filter.
Assignment #2:
The inventors of the Internet decided early on that it was too difficult for humans to refer to computer systems using dotted
decimal IP address or full decimal IP address, much less 32-bit binary IP addresses. They decided to have a list of IP addresses matched
up with corresponding human-friendly names, that any computer on the Internet could use to translate a human-friendly computer name to
an IP address (LMHOSTS files and WINS servers do this for NetBIOS names, not TCP/IP names). This is called name resolution.
The original IP specification implemented name resolution using a special text file call HOSTS. A copy of this file was stored on
every computer system on the Internet. The HOSTS file contained a list of IP addresses for every computer on the Internet, matched to
the corresponding system names. Part of an old HOSTS file could look like this:
192.168.2.1
fred
2
201.32.16.4 school2
123.21.44.16 server
Search for the file called HOSTS on your computer
Every HOSTS file on every system on the Internet was updated at 2AM. This worked well while the Internet was still small. But when it
grew to about 5000 systems, it became too tedious to maintain the HOSTS file.
Instead, the Domain Name System or DNS (another TCP/IP protocol along with ARP and IP) was created. The Domain Name
System is the system used on the Internet for the mapping of names, such as www.google.com, to IP Addresses such as 216.239.51.99.
One computer alone can’t handle all the domain name resolution
At the top of the Domain Name System, you have Root Servers running DNS software, making them DNS servers.
Just below the DNS root servers, in the hierarchy of DNS servers, is a set of DNS servers that handle what are known as
top-
level domain names such COM, ORG, NET, EDU, GOV, MIL, INT, etc.
These top-level DNS servers delegate to thousands of second-level DNS servers. They handle the millions of names like
whitehouse.gov, where whitehouse is the second level part and gov is the top level part. You may also have sub domain names, such as
north.mhteched.com. The owner of a second level domain maintains any subdomains on its own DNS servers, or its ISP’s DNS servers.
Subdomains may contain a further layer of subdomains, for example, bravo.north.mhteched.com.
Every system on the Internet also has a host name added on to the left of its domain name, such as www. A fully qualified
domain name (FQDN) contains the complete DNS name of a system, from its host name to the top-level domain name.
Every time a new domain, like bleepingcomputer.com, is registered, that domain is entered into one of the Root Servers
spread throughout the world and overseen by an organization called ICANN. Because your domain is in one of these servers, it can be
reached and understood by the rest of the users on the Internet.
Any time you connect to a site, your ISP
DNS Server must find out what name server has the
information about the domain for the site you are
trying to reach. Your ISP's DNS Server will
connect to a Root Server and ask it who the name
server is that knows the information about the site
you are trying to reach. The Root Server will tell
your ISP's DNS Server what server they should
next contact for information. Next your ISP's DNS
Server will then contact the server that the Root
Server told it to contact, where it will be given the
IP Address associated with the site you are trying to
reach.
The following flowchart illustrates this concept
As you can see, the Domain Name System is
essential in the use of the Internet. Without it, you
would not be able to type in names, but would have
to remember the numerical IP Addresses in order to
get anywhere on the Internet.
Assignment #3:
Where is DNS information typed in?
Find out the IP address of your current DNS server settings.
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Assignment #4:
What four settings have we discussed that can be set in the TCP/IP properties?
Depending on which of these had to change, we would have to go to every machine and reset these TCP/IP properties. Fortunately for us,
there is something called Dynamic Host Configuration Protocol (DHCP)
Review:
Look up the following related terms at www.techweb.com/encyclopedia.
1) domain name
2) domain name address
3) Domain name registrar
4) Domain name resolver
5) Domain name server
6) DNS
7) FQDN
8) ICANN
9) Internet domain name
10) URL
Sample Test Questions:
1) The IP address 192.23.45.123 has a default subnet mask of
A) 255.0.0.0
B) 255.255.0.0
C) 255.255.255.0
D) 255.255.255.255
2) Scott’s system wants to send data to Roger’s system. Scott’s system knows Roger’s IP address, but it doesn’t know the MAC address,
which it needs. What does the system use to request a MAC address for a known IP address?
A) ARP
B) WINIPCFG
C) IPCONFIG
D) MACIP
3) Mike is running Windows 2000. He wants to find out his MAC address and IP address. What utility can Mike use to provide this
information?
A) ARP
B) WINIPCFG
C) IPCONFIG
D) MACIP
4) The binary number 11000101 has the decimal equivalent of
A) 197 B) 169
C) 94 D) 82
5) Which of the following represents a Class A address?
A) 17.2.3.5
B) 145.16.5.6
C) 192.168.0.1
D) 255.255.255.255
6) Which of the following represents a Class C address?
A) 17.2.3.5
B) 145.16.5.6
C) 192.168.0.1
D) 255.255.255.255
7) An IPv4 address consists of __________ octets divided by dots
A) 2
B) 4
C) 8
D) TCP/IP doesn’t use octets
8) What function of an IP configuration defines which numbers in the IP address identify the network?
A) The gateway
B) DNS
C) The first octet D) The subnet mask
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9) A host is
A) any server on a TCP/IP network
B) Any device on a TCP/IP network that can send or receive data packets
C) A device on a TCP/IP network that forwards data packets to other networks
D) A device on a TCP/IP network that resolves names to IP addresses
10) What is the loopback address for IPv4?
A) 127.0.0.1
B) 0:0:0:0:0:0:0:0
C) ::1
D) 0:0:0:0:0:0:0:0
11) How many bits are in an IP address?
A) 16
B) 32
C) 64
D) None of the above
12) What is the maximum decimal value of each octet in an IP address?
A) 28
B) 255 C) 256
D) None of the above
13) The network number plays what part in an IP address?
A) It specifies the network to which the host belongs.
C) It specifies which node on the subnetwork is being addressed
D) It specifies which networks the device can communicate with
B) It specifies the identity of the computer on the network
14) Convert the binary IP address 11000000.00000101.00100010.00001011 to its decimal form
A) 190.4.34.11
B) 192.4.34.10
C) 192.4.32.11
D) None of the above
15) If using classful addressing, what portion of the IP address 129.219.51.18 represents the network?
A) 129.219 B) 129
C) 14.1
D) 1
16) Which of the following addresses is an example of a broadcast address on the network 123.10.0.0 with a subnet mask of 255.255.0.0
A) 123.255.255.255
B) 123.10.255.255
C) 123.13.0.0
D) 123.1.1.1
17) How many host addresses can be used in a Class C network?
A) 253
B) 254
C) 255
D) 256
18) What is the minimum number of bits that can be borrowed to form a subnet?
A) 1
B) 2
C) 4
D) None of the above
19) How many bits are in a subnet mask?
A) 16
B) 32
C) 64
D) None of the above
20) With a Class C address of 197.15.22.31 and a subnet mask of 255.255.255.224, how many bits have been borrowed to create a
subnet?
A) 1
B) 2
C) 3 D) None of the above
Assignment #5:
Look up Airport at www.techweb.com/encyclopedia. What is the Airport Equivalent in the PC world? 802.11b
What is Airport Extreme equivalent to in the PC world? 802.11g
Look up WiMAX. What is WiMAX? Wireless devices that operate at longer distances.
What IEEE Standard number is used by WiMAX? Uses the 802.16 Standard
Assignment #6: Download the program A-MAC Address from www.downloads.com and explore what in can do with respect to MAC
addresses.
Assignment #7: Go to http://standards.ieee.org/develop/regauth/oui/public.html and enter the first 6 hex digits of your MAC address in
the search box to find out the
Assignmeng #8: One of the easiest ways to get your MAC address is to type in the getmac command from the command line. But see if
you can spot your MAC address after running the net config workstation command.
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Sample Test Questions:
1) VLANs break up ____________ domains in a Layer 2 switched network
2) Switches, by default, only break up _________ domains.
3) What does trunking provide?
4) You connect a host switch port, but the new host cannot log into the server