Dhcp server updating dns records
"." is the root domain # from which all the TLDs branch. # Next line defines the DNS time-to-live setting $TTL 907200 ; 1 week 3 days 12 hours # The next set of lines are the "Start of Authority" record and define important # info about the domain. The reverse zone we defined earlier is located at , and should look something like this: /var/lib/bind/.rev1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 # Again, we have an origin record and a TTL entry... $TTL 907200 ; 1 week 3 days 12 hours # ..note the name of the reverse domain: ".in-addr-arpa". ( 1263187356 ; serial 10800 ; refresh (3 hours) 3600 ; retry (1 hour) 604800 ; expire (1 week) 38400 ; minimum (10 hours 40 minutes) ) NS dnsserver. This file is defined at : /var/lib/bind/dummy-block1 2 3 4 5 6 7 8 $TTL 24h @IN SOA dnsserver. Our DHCP configuration touches only one file, but has a big chunk of options we need to set for dynamic updating to work; additionally, there are some decisions to be made about how and to which hosts addresses should be distributed.
In my case, we're defining and saying # that dnsserver.is its source host, and [email protected]# is the domain maintainer. This is a # special name format used only by reverse lookup domains. # # Just like above, we now set our origin away from "." to the actual domain name, # which is ".in-addr-arpa", and then we add records. We’ll be modifying , which contains all the configuration settings for the DHCP server.
Don’t worry about filling in the names for any DHCP-assigned hosts, as the dynamic update setting we’ve just finished with will take care of allowing DHCP to add in its own hosts without you having to deal with it. Each statically-addressed host gets an A record so that the server knows how to correlate its name with its IP address. The thing to notice about the reverse zone is the name of the domain we’re working with: is used as the domain for reverse lookups for historical reasons, because DNS reverse lookups use a method codified back when was actually a working domain.
The first file we need to modify is the forward lookup zone definition, we defined a moment ago to be : /var/lib/bind/hosts1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 # This line indicates that the object we're configuring below (in this case, # bigdinosaur.org) has its origin at the "." domain. Now that the forward zone is built, we need to build the reverse zone, so that we can correlate IP addresses back to names, just like a reverse phonebook. The very last zone to define is our “dummy” zone, which we use to blackhole all DNS lookups. @ IN A 127.0.0.1 * IN A 127.0.0.1 This file’s structure is much simpler and adds an A record to return an IP address of .
The first zone is my forward lookup zone for Bigdinosaur.org, and the entry tells the DNS server that the IP addresses for all host names ending in “bigdinosaur.org” can be found in the file section is allowed to make modifications to that zone.
# The lines after that define the zone serial number, which is used to keep track # of when the zone file was modified, and then some interval definitions which # you can leave as default. First, we add # an "NS Record" to define the domain's name server... # ..an "A Record" for the domain server's IP address... A cautionary note: pay extremely close attention to syntax, especially punctuation.A .10 # ..finally "MX Records" so that e-mail for the domain's e-mail addresses # goes to the right place. Many of the options, particularly in the second, third, and fourth sections, are very similar to some of the lines from the DNS configuration, but “very similar” is not “exactly alike”.Since my domain is registred through Google Apps, # this info was all provided by Google. Cut and paste with caution—when I was originally setting this all up, I ran into a problem which had me banging my head against the wall for almost a full hour, and which all ended up coming back to a single misplaced period. Here’s the option block in my : /etc/dhcp/dhcpd.conf1 2 3 4 5 6 7 8 9 10 ddns-updates on; ddns-update-style interim; update-static-leases on; authoritative; key rndc-key allow unknown-clients; use-host-decl-names on; default-lease-time 1814400; #21 days max-lease-time 1814400; #21 days log-facility local7; And, line by line, here’s what we’re doing: : This line enables global dynamic updating.Still, all we’re going to do is set up three simple zones—that is, three separate administrative blocks—and add a few options so that servers on your LAN can use the DNS server, so the resultant set of config files won’t be too bad at all.The configuration for the DHCP server will be a lot more complex, so we’ll save it for last.