ntut.edu.tw DNS Report

Health Score: 79%

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Checked: 2 weeks before

Parent

NS records at parent servers

galaxy.cc.ntut.edu.tw [ 140.124.13.1 ]
nsbackup.ntut.edu.tw [ 60.250.162.30 ]
sun.cc.ntut.edu.tw [ 140.124.13.2 ]
[These were obtained from d.twnic.net.tw.]

Glue at parent nameservers 7/7

SUCCESS Parent nameservers know A records for your domain, Very good !

NS

Mismatched glue 0/7

The glue provided by the root servers does not match glue that provided by your authoritative DNS servers.
(sun.cc.ntut.edu.tw.	300	IN	A	140.124.13.2) present at Parent, missing at (140.124.13.1, 60.250.162.30, 140.124.13.2)
(galaxy.cc.ntut.edu.tw.	300	IN	A	140.124.13.1) present at Parent, missing at (140.124.13.1, 60.250.162.30, 140.124.13.2)
(nsbackup.ntut.edu.tw.	300	IN	A	60.250.162.30) present at Parent, missing at (140.124.13.1, 60.250.162.30, 140.124.13.2)

Nameservers A records 0/7

Some servers does not provide A records for nameservers.
missing A record(s) for (galaxy.cc.ntut.edu.tw) at nameserver 140.124.13.1
missing A record(s) for (galaxy.cc.ntut.edu.tw) at nameserver 60.250.162.30
missing A record(s) for (galaxy.cc.ntut.edu.tw) at nameserver 140.124.13.2

Nameservers report identical NS records 7/7

SUCCESS The NS records at all your nameservers are identical.

Nameservers respond 10/10

SUCCESS All of your nameservers listed at the parent nameservers responded.

Nameserver name validity 7/7

SUCCESS All of the NS records that your nameservers report are valid (no IPs or partial domain names).

Number of nameservers 5/5

SUCCESS You have 3 nameservers. You must have at least 2 nameservers (RFC2182 section 5 recommends at least 3 nameservers), and preferably no more than 7.

Lame nameservers 7/7

SUCCESS All the nameservers listed at the parent servers answer authoritatively for your domain.

Missing (stealth) nameservers 7/7

SUCCESS All your nameservers are also listed at the parent servers.

Root missing nameservers 0/7

DANGER There are nameservers not listed at your nameservers:
nsbackup.ntut.edu.tw.
sun.cc.ntut.edu.tw.

Nameservers on separate class C's 7/7

SUCCESS Nameservers are in a different networks.

public IPs 7/7

SUCCESS All of your NS records appear to use public IPs.

SOA

SOA record

SOA record is:
Hostmaster email
network.ntut.edu.tw
Serial
2018121615
Refresh
10800
Retry
3600
Expire
2419200
TTL
600

Serial agreement 7/7

SUCCESS All your nameservers agree that your SOA serial number is 2018121615 That means that all your nameservers are using the same data.

SOA MNAME 3/3

SUCCESS SOA (Start of Authority) record states that your master (primary) name server is: galaxy.cc.ntut.edu.tw That server is listed at the parent servers, which is correct.

Serial value 1/1

SUCCESS SOA serial number is: 2018121615 This appears to be in the recommended format of YYYYMMDDnn, where 'nn' is the revision. This number must be incremented every time you make a DNS change.

Refresh value 1/1

SUCCESS SOA Retry interval is : 10800 seconds. This seems OK. (Values about 3600-7200 seconds is good if not using DNS NOTIFY; RFC1912 2.2 recommends a value between 1200 to 43200 seconds (20 minutes to 12 hours)). This value determines how often secondary/slave nameservers check with the master for updates.

Retry value 1/1

SUCCESS SOA Retry interval is : 3600 seconds. This seems OK. (Values about 120-7200 seconds is good). The retry value is the amount of time your secondary/slave nameservers will wait to contact the master nameserver again if the last attempt failed.

Expire value 1/1

SUCCESS SOA Expire time is : 2419200 seconds. This seems OK. (Values 604800 to 2419200 seconds (1-4 weeks) is good). RFC1912 suggests 2-4 weeks. This is how long a secondary/slave nameserver will wait before considering its DNS data stale if it can't reach the primary nameserver.

TTL value 1/1

SUCCESS SOA Expire time is : 600 seconds. This seems OK. (about 300 to 86400 seconds or 5 min - 24 hours is good). RFC2308 suggests a value of 1-3 hours. This value used to determine the default (technically, minimum) TTL (time-to-live) for DNS entries, but now is used for negative caching.

Info

DNS trace

Trace to ntut.edu.tw
lookup ntut.edu.tw at A.ROOT-SERVERS.NET(198.41.0.4) 2 ms
A.ROOT-SERVERS.NET(198.41.0.4) refer to a.dns.tw(203.73.24.25)
lookup ntut.edu.tw at a.dns.tw(203.73.24.25) 201 ms
a.dns.tw(203.73.24.25) refer to c.twnic.net.tw(168.95.192.10)
lookup ntut.edu.tw at c.twnic.net.tw(168.95.192.10) 196 ms
c.twnic.net.tw(168.95.192.10) refer to galaxy.cc.ntut.edu.tw(140.124.13.1)
lookup ntut.edu.tw at galaxy.cc.ntut.edu.tw(140.124.13.1) 222 ms
got A record 'ntut.edu.tw IN A 140.124.13.105' from ntut.edu.tw(140.124.13.1)
Total time: 621 ms