1. Ip addressing: dhcp & dns
Chapter 5c

2. objectives Upon completion of this chapter, you should be able to:
Configure IP addresses
Identify & select valid IP addresses for networks
Configure a DHCP server
Configure a host to use DHCP for configuration
Troubleshoot & resolve IP addresses configuration and communication issues
Configure DNS addresses
Configure an IPv6 address

3. Network+ objectives
1.3 Install and configure the following networking services/applications
DHCP
Static vs dynamic IP addressing
Reservations
Scopes
Leases
Options (DNS servers, suffixes)
IP helper/DHCP relay
DNS
DNS servers
DNS records (A, MX, AAAA, CNAME, PTR)
Dynamic DNS

4. Dhcp server configuration
5.3
Dhcp server configuration

5. DHCP Overview IP configuration used to be manual
Assign IP, SM, DG, DNS
DHCP takes care of that
At home, your router is a DHCP server
At work, you may have a dedicated DHCP server
Used for general purpose/PC devices
Static addressing for routers, switches, printers, Internet-accessible devices
DHCP addresses are leased for a time period
Discuss wi-fi and when you enter another network, DHCP gets your device an IP address, SM, DG, and DNS server addresses.
DHCPv6 (DHCP for IPv6) provides similar services for IPv6 clients. One important difference is that DHCPv6 does not provide a default gateway address. This can only be obtained dynamically from the router's Router Advertisement message.

6. Dhcp everywhere

7. Dhcp: how it works
Discover: where you at? BROADCAST* of all 255’s goes to everyone but only the DHCP server responds
Offer: Do you want to use this address?
Request: I’d like to use that one. I’m accepting this offer. BROADCAST*
ACK: Thanks for shopping! Your lease is finalized. It’s all yours!
DORA!!!!!

8. activity Watch Professor Messer Video
DHCP Addressing Overview 5:15
TestOut Watch the video/script
TestOut Configure a DHCP Server Lab

9. Dhcp reservations Dynamic Allocation Static Allocation
Sever has a pool of addresses
DHCP Servers use dynamic allocation
Keeps a list of what MAC addresses used each IP address
You’ll usually get the same IP address next time
Static Allocation
You configure an IP address for a specific device (printers, switches, router ports) via MAC
Video is to Professor Messer
The DHCP Reservations area is where you would assign the range of addresses to be given out or excluded (like don’t give out these addresses because they belong to servers).
DHCP Reservations
3:16

10. Dhcp scopes The pool of addresses you tell it to give out
Along with the SM, DG, DNS server address, lease duration, etc.
DHCP Scopes
2:10

11. Dhcp leases Allocated/assigned a lease time
If you reboot, it forgets & then requests an IP
Reallocation (remember DHCP server keeps list)
Lease starts over
Timers T1
Checks in with DHCP server to renew lease (still in use) at 50% of lease time T2
If DHCP server lost, it will check in at 7/8 time to hopefully update the time & renew
DHCP Leases
4:09
50% of lease time: Example 4 day lease will check in at 2 days
7/8 time: Example 4 day lease checks in at 2 days and it can’t find the DHCP server. It tries again at 3.5 days.

12. Dhcp options Stuff in addition to IP
SM, DG, DNS, lease time
Other options include VoIP settings
Such as the Call Server IP address for the phone
DHCP Options
2:46

13. activity TestOut 5.3.3- Watch the video/script
TestOut Configure DHCP Options Lab

14. activity TestOut 5.3.5- Create DHCP Exclusions Lab
TestOut Create DHCP Client Reservations Lab
TestOut Watch the video/script
TestOut Configure a DHCP Client Lab
TestOut Practice Questions (8Q)
Complete this in 2-3 days on their own.

15. 5.4
Dhcp relay

16. Dhcp relay Your DHCP server may be on another subnet
Or a backup DHCP server is on another subnet
Broadcasts DO NOT pass routers
DHCP uses broadcasts ( )
DHCP relay
Configured on router to pass these broadcasts
Sometimes called IP Helper

17. activity TestOut 5.4.1- Watch the video/script
TestOut Configure a DHCP Relay Agent Lab
TestOut Add a DHCP Server on Another Subnet Lab
TestOut Practice Questions (3Q)
Complete in 1 day.

18. 5.5
Dns name resolution

19. Dns- the beginning Each host is assigned a number (IP address)
It’s easier to remember names though
Originally, each device had a simple text hosts file that mapped names to numbers
It had to be on each device
List got to big
Hard to update

20. Dns- now Servers that translates names to IP addresses
Local DNS servers know some, forward rest to higher authority DNS servers
The main DNS servers are called Root Servers
Other companies & ISPs have their own DNS servers that connect to the Root Servers
Your PC connects to a DNS server (usually your ISPs)
A list of root servers:
Root Servers

21. How name servers are organized
From within GCIT, you want to get to (the FULLY QUALIFIED DOMAIN NAME- FQDN)
Your PC checks its DNS cache. If not there, it goes to your local DNS server (which could be on the GCIT network or at the ISP) and it communicates its findings back to your local DNS server.
The local DNS server queries the root server. Root server responds with IP addresses of the TLD servers for .edu’s. and it communicates it back to your local DNS server.
The local DNS server requests the info from one of the TLD servers for .edu’s. The TLD server responds with the IP address of the umass.edu authoritative server.
Your local DNS server makes the request to the Umass name server which responds with the IP address of the web server host.
Your local DNS server and the client PC store the info in cache so it doesn’t have to ask again.
(FQDN)
COM- top-level domain (TLD)
Google- second-level domain
Maps- third-level domain (subdomain)

22. Dns- where it’s set
Go to command prompt & type: ipconfig /displaydns displays all cached DNS
If a web admin changes the IP address of a server, it gets set in DNS server, and the user has no idea the IP address changed.

23. Checking dns Nslookup Ipconfig /displaydns Ipconfig /flushdns
Get in the mode and then enter domain
Ipconfig /displaydns
Displays cached DNS
Ipconfig /flushdns
Removes all cached DNS entries
If DNS is not working, you won’t be able to get to websites by their host name, just their IP address.

24. activity Use nslookup, displaydns, flushdns DNS Overview 6:28
DNS Overview
6:28

25. In the dns server database
DNS server has many records to resolve names
Records include name field (domain name), address, type field (type of resource, usually Internet)
Common types of DNS records:
Type
Description A
A host’s IPv4 address
AAAA
A host’s IPv6 address MX
Identifies a Mail Server NS
Authoritative Name Server
CNAME
Holds another name for a host
CNAME Example: points to
Each record in the database has a TTL that says how long it should keep it in cache.
DNS Records
5:53

26. Configuring dns & using this

27. Review- 3q .edu, .org, and .gov are all what kind of domains?
Top-level domains
What kind of server is being used if you have to add an MX record to the DNS settings?
Mail server
A host has been assigned an IP address of What kind of address is this?
APIPA

28. activity
Unit 5c DHCP/DNS Packet Tracer Lab

29. Packet tracer lab Lab 10.2.2.7 Configure static & dynamic DHCP
Configure a DNS Server

30. activity TestOut 5.5.1- Watch the video/script
TestOut Configure DNS Addresses Lab
TestOut Create Standard DNS Zones Lab
TestOut Create Host Records Lab
TestOut Create CNAME Records Lab
TestOut Troubleshoot DNS Records Lab
TestOut Practice Questions (5Q)
Complete in 2-3 days

31. Ip addressing: dhcp & dns
Chapter 5c