Can I configure a DNS zone such that both a.b.c and b.c can serve as host names? In other words, can b.c be both a subdomain and a hostname at the same time?

Is this perhaps just a matter of serving both A and NS (for delegation) records for b in c's zone?

2 Answers 2


Yes you can! You also do somethhing similar when making example.com and www.example.com point to an A record. You will have to create the A record on the delegated zone though.

You can combine A and NS records but you can’t combine them with a CNAME record.

Note that the terms “hostname” and “subdomain” are kinda synonymous as you can createA records for www.test(.example.com.) and both wwe and test are considered a subdomain. You’re talking about a delegation of a zone here. And you can both delegate a zone and assign an A record to it (from the delegated zone, as its apex).


If you only want to have records for b.c and a.b.c subdomains are not necessary. It's completely valid to have more sub-levels in one file, for example in zonefile for c you can have

b    IN     A
a.b  IN     A

If you really want a subdomain b.c first define delegation i c zonefile.

b    IN     NS   ns.with.b.c.zone

the ns.with.b.c.zone can point on the same server, or to hosting provider for example. Is good practice to have at least two DNS server for domain. RFC1912

next define A record for b.c in zonefile for b.c

@    IN     A


b.c. IN     A
  • If I understand your example with delegation correctly, the host b.c hosts a domain server for the delegated domain b. Does this have to be the case or could it be hosted elsewhere?
    – rookie099
    Jan 25, 2019 at 9:40
  • It can be hosted everywhere, for example at hosting company. b IN NS some-ns.somecompany.com. in this case is not necessary to have following A record
    – Quantim
    Jan 25, 2019 at 9:50

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