Bootstrap Protocol (BOOTP) is a networking protocol that automatically provides devices with IP addresses and other network configuration when connecting to a network. It uses DHCP and UDP to make address requests and handle responses. When a BOOTP client boots up, it broadcasts its MAC address as a request. The BOOTP server responds with an IP address, hostname, subnet mask, and other configuration details. DHCP is an updated version of BOOTP that dynamically assigns IP addresses and other network configuration to devices on a network. A DHCP server manages a pool of IP addresses and provides them to clients through a four step request/offer process. DHCP offers benefits over static addressing like reduced errors and centralized management of addresses. DNS is a

1. Host Configuration &
Domain Name System

2. Bootstrap Protocol (BOOTP):
• Bootstrap Protocol (BOOTP) is a networking protocol which is used
by networking administration to give IP addresses to each member of
that network for participating with other networking devices by the
main server.
• It is a basic protocol that automatically provides each participant in a
network connection with a unique IP address for identification and
authentication as soon as it connects to the network. This helps the
server to speed up data transfers and connection requests.
• This shortens the connection time between the server and the client.
It starts the process of downloading and updating the source code
even with very little information.

3. Bootstrap Protocol (BOOTP):
• BOOTP uses a combination of DHCP (Dynamic Host Configuration
Protocol) and UDP (User Datagram Protocol) to request and receive
requests from various network-connected participants and to handle
their responses.
• In a BOOTP connection, the server and client just need an IP address
and a gateway address to establish a successful connection. Typically,
in a BOOTP network, the server and client share the same LAN, and
the routers used in the network must support BOOTP bridging.
• In this scenario, when the BOOTP client is booted up, it initially has no
IP configuration. Instead, it broadcasts its media access control
address to the network as a BOOTP request. The BOOTP server then
picks up the message and replies with IP address, hostname,
subnet mask, default gateway address, boot file, and transaction ID.

5. BOOTP
• BOOTP requests and replies are encapsulated in UDP datagrams

6. BOOTP Packet format
• format of the 300-byte BOOTP request and reply

7. • Opcode: is 1 for a request and 2 for a reply.
• Hardware type field: is 1 for a 10 Mbits/sec Ethernet, the same value
that is in the field of the same name in an ARP request or reply
• Hop count: is set to 0 by the client, but can be used by a proxy server
• transaction ID: is a 32-bit integer set by the client and returned by
the server. This lets the client match a response with a request. The
client should set this to a random number for each request.
• Number of seconds: can be set by the client to the time since it
started trying to bootstrap. The servers can look at this value, and
perhaps a secondary server for a client won't respond until the
number of seconds has exceeded some value, implying that the
client's primary server is down.
BOOTP Packet format

8. • client IP Addr: If the client already knows its IP address, it fills in
the client IP address. Otherwise, the client sets this to 0.
• Your IP Addr: In the latter case the server fills in your IP address with
the client's IP address.
• Gateway IP Addr: The server IP address is filled in by the server. If a
proxy server is used, that proxy server fills in its gateway IP address.
• Client hardware addr: this is the same value as in the Ethernet
header
• Server hostname: is a null terminated string that is optionally filled in
by the server.
• boot filename: The server can also fill in the boot filename with the
fully qualified, null terminated pathname of a file to bootstrap from.
BOOTP Packet format

9. Vendor-Specific Information
• This area contains optional information
for the server to return to the client.
• The first 4 bytes of this area are set to
the IP address 99.130.83.99.
This is called the magic cookie
and means there is information in the
area.
BOOTP Packet format

10. DHCP: Dynamic Host Configuration Protocol
• Dynamic Host Configuration Protocol (DHCP) is a client-server
protocol that automatically assigns an Internet Protocol (IP)
address to a device as well as other related configurations.
• Every computer on a network must have an IP address to
communicate with other devices. An IP address is an identifier
for a computer or device on a network.
• There are two ways an IP address is assigned to a computer –
static and dynamic.
• Static: A static IP is where a user assigns an IP address
manually to a computer. However, this process is tedious and
error-prone as it requires manual intervention every time a
device joins the network.

11. DHCP: Dynamic Host Configuration Protocol
• A dynamic IP is where
a computer receives an
IP address from a
DHCP server. Moreover,
a DHCP server also
assigns a device a
subnet mask, default
gateway, and the
Domain Name System
(DNS) server in addition.

12. • The assignment between the DHCP client and server follows four
steps,
1.Server Discovery: Once a device joins a network and requires an
IP address, it broadcasts a message to the network asking for it. The
DHCP server will process this request and all other devices in the
network will ignore this message
2.DHCP Offer: The DHCP server looks for an available IP address
from its pool of addresses and offers one to the requesting device
3.DHCP Request: The device responds to the DHCP server by
confirming the provided IP address
4.Acknowledgment: The DHPC server provides the IP address,
subnet mask, default gateway and the DNS server details to the
device
DHCP: Dynamic Host Configuration Protocol

13. • The IP address information assigned by DHCP is only valid for
a limited period of time and is known as a DHCP lease and the
period of validity is called the DHCP Lease time.
• When the lease expires, the client can no longer use the IP
address and has to stop all communication with the IP network
unless it requests to extend the lease via the DHCP lease
renewal cycle.
• To avoid impacts of the DHCP server not being available at the
end of the lease time, clients generally start renewing their lease
halfway through the lease period. This renewal process ensures
robust IP address allocation to devices.
DHCP: Dynamic Host Configuration Protocol

14. Benefits of DHCP
DHCP offers several benefits over static IP configuration:
1. Reliable IP address management: DHCP minimizes
configuration errors caused by manual IP address
configuration, such as typographical errors, or address conflicts
caused by the assignment of an IP address to more than one
computer at the same time Reduced Manual Intervention:
2. DHCP lets network administrators centralize and automate
the IP address configuration process. DHCP lets efficient
management of IP addresses. For example, if a device leaves
the network or moves to a different location, the assigned IP
address is removed and assigned to another device

15. Comparison between BootP and DHCP

16. Domain Name System (DNS)
• “When users type domain names into the URL bar in their
browser, DNS servers are responsible for translating those
domain names to numeric IP addresses, leading them to the
correct website.”
• DNS is a hostname for IP address translation service. DNS
is a distributed database implemented in a hierarchy of name
servers. It is an application layer protocol for message
exchange between clients and servers.
• Requirement: Every host is identified by the IP address but
remembering numbers is very difficult for the people also the IP
addresses are not static therefore a mapping is required to
change the domain name to the IP address. So DNS is used to
convert the domain name of the websites to their numerical IP

17. Domain Name
System (DNS)
Domain: There are various kinds of DOMAIN:
1.Generic domain: .com(commercial) .edu(educational)
.mil(military) .org(non profit organization) .net(similar to
commercial) all these are generic domain.
2.Country domain .in (india) .us .uk
3.Inverse domain if we want to know what is the domain name of
the website. Ip to domain name mapping. So DNS can provide
both the mapping for example to find the IP addresses of
geeksforgeeks.org then we have to type nslookup

18. Organization of Domain:
It is very difficult to find out the IP address associated to a website
because there are millions of websites and with all those websites we
should be able to generate the IP address immediately, there should
not be a lot of delay for that to happen organization of database is very
important.
DNS record: Domain name, IP address what is the validity?? what is
the time to live ?? and all the information related to that domain name.
These records are stored in tree like structure.
Namespace: Set of possible names, flat or hierarchical. The naming
system maintains a collection of bindings of names to values – given a
name, a resolution mechanism returns the corresponding value.

19. Name Server
The host requests the DNS name server
to resolve the domain name. And the
name server returns the IP address
corresponding to that domain name to the
host so that the host can future connect
to that IP address.
The client machine sends a
request to the local name server,
which , if root does not find the
address in its database, sends a
request to the root name server ,
which in turn, will route the query
to an top-level domain (TLD) or
authoritative name server.