DNS

References

• Microsoft Technet — Resource records reference

A DNS database consists of one or more zone files used by the DNS server. Each zone holds a collection of structured resource records, the following of which are supported by the DNS Server service.

• Microsoft Technet — Understanding DNS

How DNS works.

• DNS-HOWTO

Detailed explanations on how DNS work, applied to Linux.

• zytrax open — Chapter 8. DNS Resource Records (RRs)

• Wildcard DNS record (like *.example.com. 3600 IN MX 10 host1.example.com.)

How-to

Reverse DNS lookup

See dig, host and nslookup.

Transfer a domain

See OVH guide.

Prerequisite:

• Domain status record in Whois database must be ok.

whois noekeon.org|grep -i "domain status"
# Domain Status: ok https://icann.org/epp#ok

If not ok, then maybe the domain is locked. In that case, it must be unlocked first at current registrar.

• Domain must not expire soon (soon seems variable, but is between 14 days and 60 days).
• Domain must exist for at least 60 days.
• Must have the domain transfer authorisation code (AUTHINFO).

Troubleshooting

SERVFAIL

dig (and dig +notrace) fails with a SERVFAIL error code but dig +trace works:

dig +notrace miki.immie.org

# ; <<>> DiG 9.9.5-9+deb8u6-Debian <<>> +notrace miki.immie.org
# ;; global options: +cmd
# ;; Got answer:
# ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 29570
# ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

Using a different DNS server works too:

dig @8.8.8.8 miki.immie.org

Other subdomains in that zone work though:

dig +notrace kiwi.immie.org
dig +notrace mip.immie.org

Solution

Turns out that we had duplicate CNAME entries in the zone file. We delete one.

miki       10800 IN CNAME prime
miki       10800 IN CNAME prime