Compare Network Configuration Concepts Flashcards
Dynamic Host Configuration Protocol(DHCP)
A DHCP server can be used to allocate an appropriate IP address and subnet mask (plus other settings) to any host that connects to the network and requests address information.
DHCP Scope
A scope is the range of addresses that a DHCP server can offer to client hosts in a particular subnet. The scope should exclude any addresses that have been configured statically. For example, the LAN address of a SOHO router is typically 192.168.0.1 . This is also the address used by the DHCP server running on the router. The scope must exclude this address.
DHCP Leases
A host is configured to use DHCP by specifying in its TCP/IP configuration that it should automatically obtain an IP address. When a DHCP client initializes, it broadcasts a DHCPDISCOVER packet to find a DHCP server. All communications are sent using UDP, with the server listening on port 67 and the client on port 68.
Presuming it has an IP address available, the DHCP server responds to the client with a DHCPOFFER packet, containing the address and other configuration information, such as default gateway and DNS server addresses. The client may choose to accept the offer using a DHCPREQUEST packet that is also broadcast onto the network.
Assuming the offer is still available, the server will respond with a DHCPACK packet. The client broadcasts an ARP message to check that the address is unused.
DHCP Reservations
It is often useful for a host to use the same IP address. Servers, routers, printers, and other network infrastructure can be easier to manage if their IP addresses are known.
The DHCP server is configured with a list of the MAC addresses of hosts that should receive the same IP address. When it is contacted by a host with one of the listed MAC addresses, it issues a lease for the reserved IP address.
fully qualified domain name (FQDN).
Unique label specified in a DNS hierarchy to identify a particular host within a subdomain within a top-level domain.
An example of an FQDN might be “nut.widget.example”. The host name is nut, and the domain suffix is widget.example. This domain suffix consists of the domain name widget within the top-level domain (TLD) .example . A domain suffix could also contain subdomains between the host and domain name.
Each FQDN reflects this hierarchy, from most specific on the left (the host name) to least specific on the right (the TLD followed by the root). For example: pc.corp.515support.com.
Domain Name System (DNS)
IP uses a binary address value to locate a host on an internetwork. A friendly” host name is also typically assigned to each host. The host name is configured when the OS is installed. The host name must be unique on the local network.
FQDNs are assigned and managed using DNS . DNS is a global hierarchy of distributed name server databases that contain information about each domain and the hosts within those domains. At the top of the DNS hierarchy is the root, which is represented by the null label, consisting of just a period (.). There are 13 root identities (A to M) across the globe. These identities represent over 1,500 individual servers, each providing identical information from the root zone to DNS resolvers all over the world.
TLDs
Immediately below the root lie the top-level domains (TLDs). There are several types of TLDs, but the most prevalent are generic (such as .com, .org, .net, .info, .biz), sponsored (such as .gov, .edu), and country code (such as .uk, .ca, .de). DNS is operated by ICANN (icann.org), which also manages the generic TLDs. Country codes are generally managed by an organization appointed by the relevant government.
