At work there was a old physical Windows who run DNS for several small domains I got the job of transfering the DNS zones to a NSD server on a Linux VM – with lower memory footprint. I was able to transfer the zones either by copying and fixing the Window zone files (need to be fixed anyway) from C:\Windows\system32\dns\foo.ch.dns or by using dig if you can’t copy zone files but the remote DNS allows zone transfer:
dig @OriginatingNS myawesomedomain.com AXFR > myawesomedomain.com.zone
I’ve been used to edit zone files manually on my private BIND and NSD – while it compiles its own DB to be faster: It’s the same source format. But my knowhow got a bit rusty on that topic and I learned I can write less to get the same result. (less repetitive and error prone). A big thanks goes to the helping hands in #DNS on the freenode IRC, who helped me to get back in the seat and fix the strangenesses of the Windows zones and refactor the stuff .
If you have to cleanup a zone file anyway I hope this commented sample gives you some ideas:
; ; Zone file for foo.ch ; $ORIGIN foo.ch. $TTL 86400 @ IN SOA ns1.foo.ch. hostmaster.foo.ch. ( 40 ; serial number 21600 ; refresh 7200 ; retry 691200 ; expire 86400 ) ; default TTL ; NS NS ns1.otherdomain.ch. NS ns2.otherdomain.ch. ; MX MX 10 mySMTP MX 10 externalSMTP.null.ch. ; A A <IP> sub1 A <IP> sub2 A <IP> ; CNAME www2 CNAME @ www2 CNAME sub1 www1 CNAME www.null.ch.
About the SOA record: There are people who know better about TTL and other settings. But more about the mail address you put in the zone file: RFC2142 says hostmaster@domain should exist (or forwarded) to someone on charge for this DNS zone. You can put any other valid address but the RFC strongly encourages you to have hostmaster@domain available for commidity. (as is postmaser@domain btw)
If you do it manually, I’d recommend using a zone serial of YYYYMMDD01, I read that in some BIND book, I hope this is still valid.
By adding a $ORIGIN variable (don’t forget to a “.” at the end) you can already write less. Here is acorrect but long example (i.e. via AXFR from dig):
foo.ch 86400 IN A <IP> sub1.foo.ch. 86400 IN A <IP>
Short but sufficient if $TTL and $ORIGIN set:
@ A <IP> sub1 A <IP>
Explanation: @ uses $ORIGIN variable and replaces it, $TTL is also inserted automatically without mentioning it and IN can be left out as it seems to be automatically assumed of not present. For A records pointing to foo.ch you can even leave out the @, it’s also sufficient:
With CNAMEs you can also use the @ if the A record is pointing to foo.ch:
demo CNAME @ CNAME @
Be warned this one won’t work:
If you have external names, let’s say you don’t operate your own MX, you can add this entry ending with the FQDN completed with “.”
admin August 6, 2011
Posted In: Uncategorized