DHCP Configuration - CompTIA A+ 220-1101 - 2.6

00:08:58
https://www.youtube.com/watch?v=wtEx-NrqJ7I

Ringkasan

TLDRLa vidéo explique comment configurer un serveur DHCP, en commençant par déterminer une plage d'adresses IP et la durée de bail. Le serveur attribue des adresses IP dynamiquement, mais on peut effectuer des réservations pour que certains périphériques reçoivent toujours la même adresse. Les timers T1 et T2 sont introduits pour gérer le renouvellement des baux et la réassociation avec un serveur redondant. Des exemples pratiques de configuration sur des serveurs Windows et des routeurs intégrés sont fournis.

Takeaways

  • 💡 Comprendre la configuration d'un serveur DHCP.
  • 🛠️ Définir une plage d'adresses IP et une durée de bail.
  • 🔗 Importance des paramètres DNS dans la configuration DHCP.
  • 📅 Les baux DHCP doivent être renouvelés régulièrement.
  • 🔒 Réservations DHCP assurent une adresse IP fixe pour certains périphériques.
  • 🚀 Utilisation de timers T1 et T2 pour gérer les renouvellements de baux.
  • 📈 Pourquoi sélectionner des adresses d'exclusion dans le DHCP ?
  • 🔄 Réallocation d'une adresse DHCP après déconnexion du réseau.
  • 🖥️ Configuration DHCP sur un serveur Windows & routeur intégré.
  • 📊 Visualisation du processus DHCP et du cycle de renouvellement.

Garis waktu

  • 00:00:00 - 00:08:58

    Dans la configuration d'un serveur DHCP, il est essentiel de définir une plage d'adresses IP, un masque de sous-réseau, la durée de location, ainsi que les paramètres DNS et la passerelle par défaut. Le serveur DHCP attribue des adresses IP à partir d'une piscine d'adresses configurées, et il est possible de créer des réservations ou d'exclure certaines adresses. Les étapes de réservation d'adresses IP permettent de garantir qu'un périphérique reçoit toujours la même adresse IP. Lorsque un appareil reçoit une adresse IP via DHCP, celle-ci est normalement attribuée dynamiquement, mais des réservations peuvent également être faites en fonction de l'adresse MAC. Les durées de location déterminent combien de temps un appareil peut conserver l'adresse avant de devoir se réinscrire, avec des timers tels que T1 et T2 gérant la vérification et le maintien des adresses en cas d'indisponibilité du serveur DHCP.

Peta Pikiran

Video Tanya Jawab

  • Qu'est-ce qu'un serveur DHCP ?

    Un serveur DHCP attribue automatiquement des adresses IP aux périphériques d'un réseau.

  • Comment configurer les paramètres d'un serveur DHCP ?

    Il faut définir la plage d'adresses IP, la durée de bail et les paramètres DNS.

  • Qu'est-ce qu'une réservation DHCP ?

    C'est une configuration qui permet à un périphérique de toujours recevoir la même adresse IP.

  • Comment fonctionne le processus de bail d'une adresse IP ?

    Le périphérique doit renouveler son bail auprès du serveur DHCP avant l'expiration pour conserver la même adresse IP.

  • Qu'est-ce que le timer T1 ?

    C'est le moment où un périphérique tente de renouveler son bail, habituellement à la moitié de la durée du bail.

  • Qu'est-ce que le timer T2 ?

    Il s'agit d'un timer qui tente de reconnecter à un autre serveur DHCP lorsque le serveur original n'est pas disponible.

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Gulir Otomatis:
  • 00:00:02
    in a previous video we described the
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    dhcp process as seen from the
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    perspective of the workstation but what
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    are the configuration settings that we
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    need to make inside of the dhcp server
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    itself well first we'll need an ip
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    address range we'll need to understand
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    exactly what ip addresses will be
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    assigned by this particular dhcp server
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    and we'll need the associated subnet
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    mask for that ip address range we'll
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    also need to determine how long a
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    workstation can hold on to the same ip
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    address will make that configuration
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    setting under the lease duration and
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    we'll also want to configure the dhcp
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    server with dns server settings so that
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    your in stations can be configured with
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    an appropriate dns server ip address a
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    default gateway setting and if you're
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    using things like voice over ip servers
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    be nice to include the options for that
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    along with all of the other ip
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    configurations
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    when the dhcp server assigns an ip
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    address to a device it's choosing an
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    available address from a pool of
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    addresses that you've previously
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    configured inside of the dhcp server for
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    example you might have one subnet pool
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    that is 192.168.1.0.20
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    which means anything in that subnet can
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    be assigned as an ip address from the
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    dhcp server these ip scopes are usually
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    a very large contiguous range of ip
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    addresses and your dhcp server simply
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    pulls from any available address inside
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    of that range but there may be times
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    when you'd like to set a dhcp
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    reservation or exclude certain ip
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    addresses from that range and you can
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    certainly create those exceptions within
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    the dhcp server
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    here's a dhcp server that's running on a
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    windows server device this specifies the
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    scope of 165.245.44.0
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    and underneath that scope we have a
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    series of address pools so we know what
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    ip addresses will be assigned we have
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    address leases so we can view what i p
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    addresses have previously been assigned
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    we can configure ip reservations so if a
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    certain device should always receive the
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    same ip address we can configure that in
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    that section of the dhcp server and we
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    have scope options which allow us to
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    configure additional parameters for
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    example we might want to add the ip
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    address of a voice over ip gateway so
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    that all of the devices on your network
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    would know exactly what ip address to
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    contact
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    if you're using dhcp at home or in a
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    small office your dhcp server may not be
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    on a windows device it may be on an
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    embedded router this is the web front
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    end to an embedded router that shows
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    that the dhcp server is enabled the
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    start address on this network is
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    10.10.10.2
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    and the end address is 10.10.10.100
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    so we can expect this dhcp server to
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    assign addresses starting with the dot 2
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    all the way up to dot 100 this dhcp
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    server specifies the address lease time
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    in seconds which is a bit unusual but if
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    we know that 86 400 seconds is the same
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    as 24 hours this configuration works
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    just fine the gateway is configured as
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    10.10.10.1
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    and we have dns configurations that will
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    also be assigned to our local devices so
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    any device on your network that needs an
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    ip address when it starts up will
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    receive an address from this dhcp server
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    with these specific configuration values
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    for most devices connecting to a network
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    and receiving a dhcp address they're
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    receiving a dynamic assignment this
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    means they could receive any ip address
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    from that large pool of ip addresses
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    that we've previously configured and
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    after your lease period has timed out
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    those addresses will be available for
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    another person who connects to the
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    network many dhcp servers will also have
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    an automatic assignment where they will
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    keep a list of everyone who's previously
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    connected to the network and if you
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    happen to connect to the network again
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    after a short period of time away it
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    will remember your previous assignment
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    and if that ip address is still
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    available it will assign you the same ip
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    address you had originally
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    you can also take this one step further
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    by configuring a dhcp address
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    reservation which means that a device
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    connecting to the network will always
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    receive that same ip address and that ip
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    address will never be given to a
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    different device on the network this is
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    usually configured based on the mac
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    address or media access control address
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    which is the burned in address on a
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    network interface card every device has
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    a unique mac address and that allows us
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    to associate a device with a particular
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    ip address you might also see this
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    referred to as a static dhcp assignment
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    static dhcp a static assignment or an ip
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    reservation
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    here are some dhcp reservations in my
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    dhcp server on a soho network you can
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    see a mac address is listed along with
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    an ip address and the host name for this
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    device is prometheus i have another
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    device listed by mac address you can see
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    that is a different mac address in the
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    original it gets a different ip address
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    and the host name for that device is
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    odyssey this means that when prometheus
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    starts up it will always receive the ip
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    address of 192.168.1.6
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    and that ip address will never be
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    assigned to another device on this
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    network
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    when a device is dynamically assigned a
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    dhcp address it's a temporary assignment
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    after a certain amount of time that
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    device must check in again to the dhcp
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    server to let it know that it is still
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    working with that same ip address or the
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    lease will timeout and that ip address
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    will be available for others the amount
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    of time in that lease is determined by
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    the configuration within your dhcp
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    server we saw on my dhcp server the
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    lease times are 24 hours but you can
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    administratively configure that to be
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    any value you'd like there's also a
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    reallocation process that can occur if
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    you reboot a device or you leave the
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    network and then return to the network
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    it will renew that lease and continue
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    using the same ip address and there may
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    be times when you would like to
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    administratively or manually release
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    that ip address hand it back to the dhcp
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    server and then either leave the network
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    or request a new address from the dhcp
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    server
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    when a device receives an ip address
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    from a dhcp server there's a timer that
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    starts that is the length of the lease
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    time that's configured for that dhcp
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    server we mentioned earlier that once
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    that lease timer has expired that ip
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    address is returned to the dhcp server
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    and it can be assigned to others but
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    during that lease process there are
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    other timers you should know about one
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    is called the t1 timer this checks in
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    with the dhcp server halfway through the
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    lease time so if your lease time was
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    eight days this t1 timer which is 50
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    percent of the lease time by default
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    will check in after four days and let
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    the dhcp server know that we would like
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    to keep this ip address for another
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    lease duration at that point the timer
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    resets to eight days and we start
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    counting down again
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    there may be times though that a dhcp
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    server is unavailable and you're not
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    able to check in with that t1 timer
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    after four days if that dhcp server
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    never returns to the network then the
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    lease time continues to count down and
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    once you get to 7 8 of that lease time
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    or 87 and a half percent of that lease
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    time it will try rebinding with any
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    other dhcp server that you might have on
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    the network so that it can retain that
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    ip address this is the t2 timer and it
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    gives every device on the network a
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    chance to keep its ip address by
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    rebinding with a redundant dhcp server
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    let's look visually at how this dhcp
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    process might occur let's say in this
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    particular network the lease time is 8
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    days in length that means your t1 timer
  • 00:07:42
    if it's 50 percent of that time would be
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    four days and a seven eighths timer of
  • 00:07:47
    t2 would be seven days in length so
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    let's look at this device which has been
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    given an ip address and each one of
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    these blocks is a single day somewhere
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    after the fourth day or after 50 percent
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    of this time has gone by and the t1
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    timer has gone off it will want to renew
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    this ip address by contacting the dhcp
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    server and letting it know that it would
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    like to renew that particular lease once
  • 00:08:12
    that process is complete the timer
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    restarts and we have another dhcp lease
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    process that will occur
  • 00:08:18
    however during the second lease process
  • 00:08:20
    our original dhcp server is no longer
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    available so we're not able to check in
  • 00:08:25
    after that t1 timer has completed this
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    means that we'll go all the way into the
  • 00:08:30
    rebinding period with the t2 timer or in
  • 00:08:33
    this particular case after seven days
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    have elapsed once we're able to contact
  • 00:08:37
    that redundant dhcp server after the t2
  • 00:08:40
    timer has expired the process then
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    begins again starting at day one and we
  • 00:08:45
    have another eight days in our lease
  • 00:08:57
    you
Tags
  • DHCP
  • Serveur DHCP
  • Plage d'adresses IP
  • Réservations DHCP
  • Température des baux
  • Réseau
  • Routeur
  • Configuration
  • Adresse IP
  • DNS