What is DHCP and DNS?

DHCP is a protocol known as Dynamic Host Configuration Protocol. Its main purpose is to assign different IP addresses to devices on a network.Network administrator has to assign IP addresses when a user connects to internet through a machine. By using this protocol network administrator's work become easier because he does not have to assign IP addresses manually as using DHCP this process of assigning IP addresses becomes automated. DNS is also a internet protocol and is known as Domain Name Server orDomain Name Service. Its purpose is to translate domain names into IP addresses. Whenever we use a domain name, then a service is used for translating domain names into IP addresses and is known as DNS. For example, the domain name www.bigcity.com might translate to192.103.202.2. So what DNS did in above example as it translates the name "Bigcity" into corresponding IP address.If one DNS server does not know how to translate the particular domain name it asks another DNS server and this process continued until the correct IP address is returned. As in above example, if one domain server does not know how to translate www.bigcity.com then it will move to another DNS until the corresponding IP address192.103.202.2 is returned.

DHCP stands for  Dynamic Host Configuration Protocol. Which is used in a network to assign IP address,  gateway & name servers dynamically.

DNS stands for Domain Name System or Domain Name Server. It is used to resolve Fully Qualified Domain Name into IP Address (i.e. Forward Lookup) and  IP Address into Fully Qualified Domain Name (i.e. Reverse Lookup).

DHCP and DNS are two different protocol

DHCP: It automatically configures IP for your host.To get automatic IP you will require a DHCP server into your LAN.DHCP uses UDP port67(Server) and port68(client). It uses broadcast

DNS: Stands for domain name system.It means it resolves name to IP and reversy IP to name

When you ping www.yahoo.com it resolves IP address to 87.248.122.122. Rversely it resolves IP to name too.None of your device can understand name.So DNS server is needed to resolve name to IP and IP to name.DNS uses UDP port53 for query.It uses TCP port53 for its zone transfer.

DHCP by short form for Dynamic Host Configuration Protocol is used to assign IP address, Default gateway, subnet mask and even DNS address automatically from the router.

DNS by short form for Domain name space is used to translate the Domain names to Numerical values for locating computer services and devices worldwide.

DHCP : automatically assign IP address to the host and it assign subnet mask,default gateway,dns adress etc . as per the requirement.

DNS : Main purpose of DNS is address resolution ie, Ip address to host name and vise versa

DHCP signifie Dynamic Host Configuration Protocol. Il s'agit d'un protocole qui permet à un ordinateur qui se connecte sur un réseau d'obtenir dynamiquement (c'est-à-dire sans intervention particulière) sa configuration (principalement, sa configuration réseau). Vous n'avez qu'à spécifier à l'ordinateur de se trouver une adresse IP tout seul par DHCP. Le but principal étant la simplification de l'administration d'un réseau

DNS signifie Domain Name System (Systeme de noms de domaine). En informatique, le DNS est un systeme permettant d'associer une adresse IP à un nom de domaine.

DNS this is internet protocol and is known as Domain Name Server or Domain Name Service. Its purpose is to translate domain names into IP addresses.DHCH this is Dynamic host configuration protocol that gives hundreds of IP that automacaly assigned to the client.

Dynamic Host Configuration Protocol (DHCP)

Mainly used to Automatically assign IP adds to clients & Devices in ur network.

Domain Name System (DNS)

Mainly used to resolve the names of domain to it's numerical IP add. "as phone Index"

DHCP is used to automatically allocate IP Addresses to client  PC on your netwok

DNS is used to Resolve IP address to hostname and Hostname to IP address.

But you should also understand that DHCP & DNS both are integrated , mean when the client takes an IP address from DHCP it will also registered in DNS  or updated the previous entry if ip address is changed of your pc.

Domain Name System (DNS) servers provide name resolution for network clients. DNS maintains (among other things) information that links a computer's fully qualified domain name (FQDN) to its assigned IP address(es).

While DHCP provides a powerful mechanism for automatically configuring client IP addresses, until recently DHCP did not notify the DNS service to update the DNS records on the client; specifically, updating the client name to an IP address, and IP address to name mappings maintained by a DNS server.

Without a way for DHCP to interact with DNS, the information maintained by DNS for a DHCP client may be incorrect. For example, a client may acquire its IP address from a DHCP server, but the DNS records would not reflect the IP address acquired nor provide a mapping from the new IP address to the computer name (FQDN).

In Windows 2000, DHCP servers and clients can register with DNS to provide this update service if the DNS server supports DNS with dynamic updates. The Windows 2000 DNS service supports dynamic updates. For more information, see the chapter "Windows 2000 DNS" in this book

A Windows 2000 DHCP server can register with a DNS server and update pointer (PTR) and address (A) resource records on behalf of its DHCP-enabled clients using the DNS dynamic update protocol.

The ability to register both A and PTR type records lets a DHCP server act as a proxy for clients using Microsoft Windows 95 and Windows NT 4.0 for the purpose of DNS registration. DHCP servers can differentiate between Windows 2000 and other clients. An additional DHCP option code (option code81) enables the return of a client's FQDN to the DHCP server. If implemented, the DHCP server can dynamically update DNS to modify an individual computer's resource records with a DNS server using the dynamic update protocol. This DHCP option permits the DHCP server the following possible interactions for processing DNS information on behalf of DHCP clients that include Option Code81 in the DHCPRequest message they send to the server:

• The DHCP server always registers the DHCP client for both the forward (A-type records) and reverse lookups (PTR-type records) with DNS.

• The DHCP server never registers the name-to-address (A-type records) mapping information for DHCP clients.

• The DHCP server registers the DHCP client for both forward (A-type records) and reverse lookups (PTR-type records) only when requested to by the client

DHCP and static DNS service are not compatible for keeping name-to-address mapping information synchronized. This might cause problems with using DHCP and DNS together on a network if you are using older, static DNS servers, which are incapable of interacting dynamically when DHCP client configurations change.

To avoid failed DNS lookups for DHCP-registered clients when static DNS service is in effect, do the following steps:

1. If WINS servers are used on the network, enable WINS lookup for DHCP clients that use NetBIOS.

2. Assign IP address reservations with an infinite lease duration for DHCP clients that use DNS only and do not support NetBIOS.

Wherever possible, upgrade or replace older, static-based DNS servers with DNS servers supporting updates. Dynamic updates are supported by the Microsoft DNS service, included in Windows 2000.

Additional Recommendations

When using DNS and WINS together, consider the following options for interoperation:

• If a large percentage of clients use NetBIOS and you are using DNS, consider using WINS lookup on your DNS servers. If WINS lookup is enabled on the Microsoft DNS service, WINS is used for final resolution of any names that are not found using DNS resolution. The WINS forward lookup and WINS-R reverse lookup records are supported only by DNS. If you use servers on your network that do not support DNS, use DNS Manager to ensure that these WINS records are not propagated to DNS servers that do not support WINS lookup.

• If you have a large percentage of computers running Windows 2000 on your network, consider creating a pure DNS environment. This involves developing a migration plan to upgrade older WINS clients to Windows 2000. Support issues involving network name service are simplified by using a single naming and resource locator service (such as WINS and DNS) on your network. For more information, see "Windows Internet Name Service" and "Windows 2000 DNS" in this book.

DNS is from Domain Name Service

when you open your broswer and try to open your Email do you see in the address bar any IP adress ?No you see only letters called URL

DNS find the IP form an URL

try type " www.google.com" in fact on the internet you cannot use this as distenation address you should translate it to IP address and that what DNS do.

DHCP in brief provide your device with IP configration such IP Address and Subnet Mask and Defult Gateway to can connect to other device on the networkif DHCP not work you should enter this information manully