How does a dhcp client communicate which offered ip address it will accept from which dhcp server?

The server will quickly and automatically assign an IP address and some related network configuration parameters. Once the device has accepted the assignment, it can communicate with both the internal network and the public internet.

Relevant parameters

In addition to assigning IP addresses, these servers also provide relevant parameters, known as DHCP options. The Internet Assigned Numbers Authority (IANA), the global coordinator of IP addresses, defines available DHCP parameters.

Options number in the hundreds. Key among them is how long the IP address can be used—known as the lease time. They also include the default gateway, its subnet mask, and its DNS server.

Some additional definitions

To clarify, let’s quickly define some of these terms we just mentioned:

• A default gateway transfers data back and forth between the local network and the internet, or between local subnets.
• IP networking uses a subnet mask to separate the host address and the network address portions of an IP address.
• A DNS server resolves names to IP addresses, translating domain names that we easily remember, like bluecatnetworks.com, into IP addresses like 104.239.197.100.

Dynamic IP addressing with DHCP

The assignment of IP addresses happens dynamically within a given address range. As a result, a device connected to the network doesn’t have a forever address. The IP address can periodically change as its lease time expires unless the lease is successfully renewed.

For services that always need to be on, a static IP address is often a better option. Corporate enterprises commonly use static IP addresses for hardware like mail servers. Certainly, a DHCP server should have a static IP address.

However, there are drawbacks to dedicating a specific IP address to a device or service. A network administrator must manually assign, configure, and track the IP address. It’s a time-consuming task. Oftentimes, it requires the admin to physically be with the device.

Meanwhile, dynamic IP addresses are usually the preferred choice because they:

• Cost less to manage than static IP addresses;
• May offer more privacy and security with a constantly changing IP address; and
• Don’t require manual administration when a device roams from one subnet to another.

DHCP communications protocol

Communications to fulfill a DHCP request involves both the server and client. Furthermore, a relay agent or IP helper often facilitates communication between the two. Relay agents receive broadcast DHCP messages from clients and then re-send those messages with configuration information to servers.

Communication happens via small units of data, called packets, that are routed through a network. Networking protocols like IP govern all its rules.

Most of the time, communication occurs in four steps. Briefly, they are:

1. A discover packet is sent from the client to the server.
2. The server replies to the client with a DHCP offer packet containing an IP address.
3. The client receives and validates the offer, then sends a request packet back to the server to accept the address.
4. The server sends an acknowledgement packet back to the client to confirm the chosen IP address.

With this in mind, one final point: DHCP alongside DNS and IP address management (IPAM) are together known as DDI. Want to know how to define DDI or how it works to form a complete management solution? The BlueCat platform is the place to start.

Before a DHCP server can hand out addresses, which of the following steps must be completed?

DHCP scope must be created and activated.

The DHCP server must be created and authorized.

DHCP standards define multiple methods to allocate IP addresses. What are they?

Dynamic, automatic, and manual

During DHCP lease negotiation, what happens if the client requests an IP address from the server but the server has already assigned the offered IP address?

The server responds with a DHCPNAK message to the client.

For DHCP address allocation, by how much is network traffic reduced related to periodic lease renewal messages when switching from dynamic allocation to automatic allocation?

100 percent because dynamic address allocation requires periodic lease renewal messages whereas automatic does not

How are DHCP settings labeled in a Windows computer's network interface?

Obtain an IP address automatically

How do DHCP servers respond to a DHCPDISCOVER message?

How does DHCP scope creation differ in Windows Server 2012 and Windows Server 2012 R2 compared to prior Windows Server versions?

In Windows Server 2012 R2, creating the scope is done separately, after adding the DHCP Server role.

How does a DHCP client communicate which offered IP address it will accept from which DHCP server?

The client sends a DHCPREQUEST message to all servers with the IP address of the chosen DHCP server.

How far into the lease period does a DHCP client begin requesting renewal of the IP address?

50 percent, or at 4 days into the lease

To make use of Pre-boot Execution Environment (PXE) and Windows Deployment Services (WDS), what special configuration do you need on the server and client?

The DHCP server on the network must have a custom PXEClient option (option 60) configured with the location of the WDS server on the network.

What are the advantages of using a distributed DHCP infrastructure?

All the client/server network traffic is local, so minimal DHCP traffic on routers

Clients have ready access to DHCP servers

What is the default lease period for DHCP dynamic address allocation?

What is the first packet sent to a DHCP server when a computer boots up?

What is the key benefit of DHCP manual IP address allocation over manually configuring the IP address by person?

This prevents accidental duplication of permanently assigned IP addresses.

What kinds of servers should NOT be DHCP clients?

Domain controllers, Internet web servers, and DHCP servers

What service does Dynamic Host Configuration Protocol (DHCP) provide?

Configures the IP address and other TCP/IP settings on network computers

Which of the following Windows PowerShell cmdlets creates an IPv4 DHCP scope?

Which of the following roles must be installed in order to deploy a DHCP Relay Agent on Windows Server 2012 R2?

Which of the following steps must be completed in order to do ensure a network printer is assigned the same address through the DHCP server?

Create a reservation in the DHCP scope

Your DHCP servers are burdened with heavy traffic, most related to IP address renewals. Unfortunately, virtually all the IP addresses in each of your subnets are allocated. Which option is the best way to lower the renewal traffic?

Deploy additional DHCP servers on the most burdened subnets.

A DNS server receives updated information. Other DNS servers have outdated information cached. What determines the amount of time that the old DNS data remains cached on a server and an update might occur?

Time To Live (TTL) specified by each DNS server's administrator

At what level of the DNS hierarchy are actual hosts, apart from the root servers?

At the second-level domain level

Concerning DNS domain hierarchy, what are examples of global top-level domains?

Concerning DNS, what is negative caching?

When a DNS server receives information about a non-existent host

What do you call the source responsible for maintaining a domain’s resource records?

The domain name part of a DNS name is _______ and consists of two or more words, separated by ______.

The typical query one DNS server sends to a root name server is called a(n) _______.

What DNS server represents the top of the DNS hierarchy?

What are some best practices when creating internal DNS namespaces?

Avoid an excessive number of domain levels

What are the servers at the top of the DNS hierarchy called

What client applications utilize DNS to resolve host names into IP addresses?

All Internet applications working with host names must use DNS to resolve host names into IP address

What is the character limit on individual domain names, and the limit on the Fully Qualified Domain Names (FQDNs)?

What is the default TTL for a Windows Server 2012 R2 DNS server?

What is the primary benefit of a DNS forwarder?

Reducing the traffic and making efficient use of available bandwidth across the network perimeter

What is the primary purpose of name caching?

Name caching enables the second name resolution request for the same name to bypass the referral process

When a DNS server communicates a name resolution query to another DNS server, what type of datagram is used, and over what port?

When using DNS for name resolution only, why should a company consider using DNS servers outside the network perimeter?

Less traffic crossing the network perimeter

Who is responsible for the ratification of new top-level domains?

Internet Corporation for Assigned Names and Numbers (ICANN)

Why is the DNS service included in Windows Server 2012 R2 integrated with DHCP service?

To allow a DHCP server to request a DNS server to update or create a record.

You registered the domain name contoso.com. The FQDNs seattle.contoso.com and halifax.contoso.com are examples of different _____.

subdomains of contoso.com

How does DHCP work How does a client receive a DHCP address?

How does DHCP communicate?

How does a DHCP server offer the client an IP address?

What process does DHCP use to give an IP address to a device?