The dynamic host configuration protocol (dhcp) is an essential resource when configuring a large amount of machines in a cluster. Using DHCP frees you from configuring each machine’s network settings individually. A DHCP server allows you to maintain network settings out of a centralized database to reduce the amount of overhead required in maintaining a cluster.
These options are designed to be placed in the dhcpd.conf file. Obviously, you won’t need to select each attribute here for your configuration file; only the needed attributes are used.
Here’s a list of the options from the dhcp-options man page, alphabetized for easy reference. These are taken from the Internet Software Consortium’s (ISC) version of DHCP. These options enable you to fully customize your network parameters at boot time. The most common parameters suitable for clustering are included:
option all-subnets-local flag;—. Specifies whether the client can assume that all subnets of the IP network to which the client is connected use the same maximum transmission unit (MTU) as the subnet of that network to which the client is directly connected.A value of 1 indicates that all subnets share the same MTU. A value of 0 means the client assumes that some subnets of the directly connected network might have smaller MTUs.
option arp-cache-timeout uint32;—. Specifies the timeout, in seconds, for ARP cache entries.option bootfile-name string;—. Identifies a bootstrap file. If supported by the client, it has the same effect as the filename declaration. BOOTP clients are unlikely to support this option. Some DHCP clients support it, and others actually require it.option broadcast-address ip-address;—. Specifies the broadcast address in use on the client’s subnet. Legal values for broadcast addresses are specified in section 3.2.1.3 of STD 3 (RFC1122).option default-ip-ttl uint8;—. Specifies the default time to live (TTL) that the client uses on outgoing datagrams.option default-tcp-ttl uint8;—. Specifies the default TTL that the client uses when sending TCP segments. The minimum value is 1.option domain-name-servers ip-address(s);—. Specifies a list of Domain Name System (DNS)(STD 13, RFC 1035) name servers available to the client. Servers are listed in order of preference.option domain-name string;—. Specifies the domain name that the client uses when resolving hostnames through the DNS.option host-name string;. —Specifies the name of the client. The name might or might not be qualified with the local domain name. (It is preferable to use thedomain-nameoption to specify the domain name.) See RFC 1035 for character set restrictions.option interface-mtu uint16;—. Specifies the MTU to use on this interface. The minimum legal value for the MTU is 68.option log-servers ip-address(s);—. Specifies a list of MIT-LCS User Datagram Protocol (UDP) log servers available to the client. Servers should be listed in order of preference.option lpr-servers ip-address(s);—. Specifies a list of RFC 1179 line printer servers available to the client. Servers should be listed in order of preference.option max-dgram-reassembly uint16;—. Specifies the maximum size datagram that the client is prepared to reassemble. The minimum value legal value is 576.option merit-dump string;—. Specifies the pathname of a file to which the client’s core image is dumped in the event that the client crashes. The path is formatted as a character string consisting of characters from the Network Virtual Terminal (NVT) ASCII character set. (The ASCII set is a standard using 7-bit codes for characters.)option nis-domain string;—. Specifies the name of the client’s Sun Network Information Services (NIS) domain. The domain is formatted as a character string that consists of characters from the NVT ASCII character set.option nis-servers ip-address(s);—. Specifies a list of IP addresses that indicates NIS servers available to the client. Servers should be listed in order of preference.option nisplus-domain string;—. Specifies the name of the client’s NIS+ domain. The domain is formatted as a character string that consists of characters from the NVT ASCII character set.option nisplus-servers ip-address(s);—. Specifies a list of IP addresses that indicates NIS+ servers available to the client. Servers should be listed in order of preference.option ntp-servers ip-address(s);—. Specifies a list of IP addresses that indicates NTP (RFC 1035) servers available to the client. Servers should be listed in order of preference.option path-mtu-aging-timeout uint32;—. Specifies the timeout, in seconds, to use when aging Path MTU values discovered by the mechanism as defined in RFC 1191.option path-mtu-plateau-table uint16(s);—. Specifies a table of MTU sizes to use when performing Path MTU Discovery as defined in RFC 1191. The table is formatted as a list of 16-bit unsigned integers, ordered from smallest to largest. The minimum MTU value cannot be smaller than 68.option routers ip-address(s);—. Specifies a list of IP addresses for routers on the client’s subnet. Routers are listed in order of preference.option smtp-server ip-address(s);—. Specifies a list of SMTP servers available to the client. Servers should be listed in order of preference.option static-routes ip-address ip-address(s);—. Specifies a list of static routes that the client installs in the routing cache. If multiple routes to the same destination are specified, they are listed in descending order of priority.The routes consist of a list of IP address pairs. The first address is the destination address, and the second address is the router for the destination.
The default route (0.0.0.0) is an illegal destination for a static route. To specify the default route, use the
routersoption.
option subnet-mask ip-address;—. Specifies the subnet mask for the client. If one isn’t declared, the DHCPD server uses the subnet from the current subnet.option tcp-keepalive-interval uint32;—. Specifies the interval, in seconds, that the client TCP waits before sending a keepalive message on a TCP connection. The time is specified as a 32-bit unsigned integer. A value of zero indicates that the client is generating keepalive messages on connections unless specifically requested by an application.option tftp-server-name string;—. Identifies a TFTP server and, if supported by the client, has the same effect as the server-name declaration. BOOTP clients are unlikely to support this option. Some DHCP clients support it, and others actually require it.option time-offset int32;—. Specifies the offset of the client’s subnet in seconds from Coordinated Universal Time (UTC).option time-servers ip-address(s);—. Specifies a list of RFC 868 time servers available to the client. Servers should be listed in order of preference.option x-display-manager ip-address(s);—. Specifies a list of systems that are running the X Window System Display Manager and are available to the client. Addresses should be listed in order of preference.