If you can see this check that
After the SOA in a named forward zone file with an origin of hello.com, which
of the following lines would create:
- hello.com having a nameserver called ns1.hello.com
- hello.com having an IP address the same as www.hello.com
- www.hello.com having an IP address 10.0.1.1
- ns1.hello.com having an IP address 10.0.1.2
A. |
1D IN NS ns1.
CNAME www.
ns1. 1D IN A 10.0.1.2
www. 1D IN A 10.0.1.1
|
B. |
1D IN NS ns1
CNAME www
ns1 1D IN A 10.0.1.2
www 1D IN A 10.0.1.1
|
C. |
1D IN NS 10.0.1.2.
A www.hello.com.
ns1 1D IN CNAME 10.0.1.2.
www 1D IN CNAME 10.0.1.1.
|
D. |
1D IN NS ns1.hello.com
CNAME www.hello.com
ns1.hello.com 1D IN A 10.0.1.2
www.hello.com 1D IN A 10.0.1.1
|
E. |
1D IN NS ns1.hello.com.
hello.com CNAME www
ns1 1D IN A 10.0.1.1
www 1D IN A 10.0.1.2
|
1-sa-19
The trailing dot after ns1 (etc) stops the origin name being added to the names. We really need ns1 to be ns1.hello.com, so the trailing dots are errors.
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0-sa-19
Good.
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3-sa-19
Trailing dots at the end of an IP number is an error.
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2-sa-19
The trailing dot at the end of a hostname stops the origin name being added to the names. We really need ns1.hello.com to be ns1.hello.com. and not ns1.hello.com.hello.com., so the trailing dots are needed here.
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4-sa-19
Here hello.com does not have a trailing dot, and is likely to be rewritten as hello.com.hello.com., which would be incorrect.
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