NS record in bind9 zone file
It is perfectly alright to have a domain name/zone-file pointing to name-servers outside of that domain i.e. it is perfectly alright to use ns1.example.com
as the name-server for the example.org
domain.
Not only means that you don't need Glue records in the example.org
zone, it is often easier to administer as well.
I think you made a slight conceptual mistake in thinking that external NS records such as ns1.example.com
imply that resource records for the example.org
domain should also be retrieved from the example.com
zone data. That is not the case, the NS record only points to a host running the name service for that domain, but the resource records will come from the zone data specific for the example.org
domain.
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Comments
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sylye over 1 year
I met a strange scenario today.
Normally when we setup a bind9 zone record, we put the NS record same as our ORIGIN. However today I found one working bind9 setup in the production site which has the NS record pointing to another domain:
[data/cat_com.zone]
$ORIGIN cat.com. $TTL 600 @ IN SOA ns.tree.com. hostmaster.cat.com. ( 2015030200 21600 3600 604800 86400 ) IN NS ns.tree.com. IN NS ns2.tree.com. IN MX 10 cat.com. ns IN A 1.2.3.124 ns2 IN A 1.2.3.124 host19 IN A 1.2.3.66
And in the record of tree.com: [data/tree_com.zone]
$TTL 600 @ IN SOA ns.tree.com. hostmaster.tree.com. ( 2015030200 ; serial 28800 ; refresh 7200 ; retry 3600000 ; expire 86400 ; default_ttl ) @ IN NS ns.tree.com. @ IN NS ns2.tree.com. @ IN MX 10 mail.tree.com. tree.com. IN A 1.2.3.66 ns.tree.com. IN A 1.2.3.124 ns2.tree.com. IN A 1.2.3.124
And in the named.conf, it has this:
zone "tree.com" { type master; file "data/tree_com.zone"; }; zone "cat.com" { type master; file "data/cat_com.zone"; };
So when I try to resolve an A record in cat.com, let say host19.cat.com, I can get the record 1.2.3.66. This is strange because according to the SOA zone file, the NS record is pointing to ns.tree.com, and in the SOA zone file of tree.com, there is no information of host19.cat.com. How does the dns resolving process can work without error in this case ? Does the NS record play a role here or it's only the named.conf that decide which SOA zone file should be used (in this case, cat.com will be referring to cat_com.zone file), and the NS record in cat.com SOA didn't mean anything ?
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MadHatter about 9 yearsIt's best not to redact domain names and IP addresses in DNS questions, but if you feel you must, PLEASE redact domain names in accordance with RFC6761 and IP addresses in accordance with RFC5737. See meta.serverfault.com/questions/963/… for more complete details on local policy.
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