IP Services // Lesson 03

DHCP & DNS.

Explain how DHCP supplies host configuration and DNS maps human-friendly names to network data.

DHCP DORALeaseDefault gatewayDNS recordsResolvers
01 // Mental model

Start with the big picture.

Automatically supplies an address, mask/prefix, gateway, DNS servers and lease information.

CCNA focus: When a host has an address but names fail, separate reachability from resolution: test the destination IP, inspect DNS settings, then query the resolver.
02 // Building blocks

Know what each part does.

01

DHCP

Automatically supplies an address, mask/prefix, gateway, DNS servers and lease information.

02

DORA

IPv4 clients commonly move through Discover, Offer, Request and Acknowledgement.

03

DNS

A distributed naming system that resolves names to records such as IPv4 A and IPv6 AAAA.

04

Different jobs

DHCP configures a client; DNS helps applications find named resources.

03 // Compare and recognise

Read the clues.

ItemWhat to remember
DHCP UDP portsServer 67 and client 68 for IPv4.
DNS portUsually UDP 53; TCP 53 is also used for cases such as larger responses and zone transfers.
A / AAAAIPv4 address record / IPv6 address record.
LeaseA time-bounded assignment that a client renews.
04 // Client startup path

Client startup path.

1. Client broadcasts DHCPDISCOVER
2. Server replies with DHCPOFFER
3. Client sends DHCPREQUEST
4. Server confirms with DHCPACK
5. Client asks its configured resolver for app.baznetic.local
6. DNS returns the matching record

Read the example from top to bottom, then verify the resulting state. Configuration is only complete when the output matches the intended design.

05 // Exam and troubleshooting

Turn facts into a method.

  • Server 67 and client 68 for IPv4.
  • Usually UDP 53; TCP 53 is also used for cases such as larger responses and zone transfers.
  • IPv4 address record / IPv6 address record.
  • A time-bounded assignment that a client renews.
Exam checkpoint: When a host has an address but names fail, separate reachability from resolution: test the destination IP, inspect DNS settings, then query the resolver.
06 // Check yourself

DHCP & DNS quiz.

1. What is the correct DHCPv4 DORA order?

2. Which DNS record maps a name to an IPv6 address?

3. Which UDP port does a DHCPv4 server listen on?

4. What does a DHCP lease control?

5. A client can ping an IP but not its hostname. Which service should be checked first?

Score: 0 / 5