DNS: Difference between revisions
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=== Reverse DNS lookup === |
=== Reverse DNS lookup === |
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See [[Linux Commands#dig|dig]], [[Linux Commands#host|host]] and [[Linux Commands#nslookup|nslookup]]. |
See [[Linux Commands#dig|dig]], [[Linux Commands#host|host]] and [[Linux Commands#nslookup|nslookup]]. |
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== Troubleshooting == |
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=== SERVFAIL === |
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<code>dig</code> (and <code>dig +notrace</code>) fails with a '''SERVFAIL''' error code but <code>dig +trace</code> works: |
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<source lang=bash> |
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dig +notrace miki.immie.org |
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# ; <<>> DiG 9.9.5-9+deb8u6-Debian <<>> +notrace miki.immie.org |
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# ;; global options: +cmd |
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# ;; Got answer: |
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# ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 29570 |
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# ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1 |
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</source> |
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Using a different DNS server works too: |
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<source lang=bash> |
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dig @8.8.8.8 miki.immie.org |
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</source> |
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Other subdomains in that zone work though: |
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<source lang=bash> |
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dig +notrace kiwi.immie.org |
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dig +notrace mip.immie.org |
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</source> |
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;Solution |
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:Turns out that we had duplicate ''CNAME'' entries in the zone file. We delete one. |
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miki 10800 IN CNAME prime |
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miki 10800 IN CNAME prime |
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Revision as of 09:48, 20 June 2016
References
- 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.
- How DNS works.
- Detailed explanations on how DNS work, applied to Linux.
How-to
Reverse DNS lookup
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