On 06.08.2019 03:32, Paulina wrote:
On Mon, Aug 5, 2019, at 06:50, Paulina wrote:
I have been using a cloud host, it seems I have a unnormal DNS resolver
entry:
And what exactly is unnormal in:
nameserver 127.0.0.53
options edns0
???
Sorry my mistake.
After checking the documents I just know what's the difference between Caching
server and
auth-server for DNS queries.
So it seems I am using a caching server whose IP addr is 127.0.0.53.
Does this article provide any help for you ?
https://askubuntu.com/questions/1012641/dns-set-to-systemds-127-0-0-53-how-to-change-permanently
I got this by asking Google for "what is 127.0.0.53"
Similarly, asking for "what is LLMNR" gets you this :
https://en.wikipedia.org/wiki/Link-Local_Multicast_Name_Resolution
and I also find plenty of information that suggests that you should disable it..
(but I don't have any experience with it, or personal knowledge that says that
this is true)
Also (but this is a different thing) :
See : https://en.wikipedia.org/wiki/Dnsmasq
You will find plenty of descriptions of dnsmasq on the WWW, but as a short
primer :
- dnsmasq runs as a daemon on you local system, and listens for DNS requests on
127.0.0.1:53
- the "DNS resolver" on your localhost is configured to "ask" dnsmasq first, whenever an
application has a DNS query
- when dnsmasq receives a DNS query, it consults its local cache first, then the local
"hosts" file, and then (if it does not find the answer there), itself is configured to ask
one or more external DNS servers. (and if it gets a result from there, it puts it in its
local cache, for a while).
But isn't this addr a loopback IP? I was not sure about it.
I was thinking the caching server should be 8.8.8.8 etc.
(base) pyh@ubuntu-18:~$ dig google.com.hk
; <<>> DiG 9.11.3-1ubuntu1.5-Ubuntu <<>> google.com.hk
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 58759
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
;; QUESTION SECTION:
;google.com.hk. IN A
;; ANSWER SECTION:
google.com.hk. 22 IN A 172.217.31.131
;; Query time: 1 msec
;; SERVER: 127.0.0.53#53(127.0.0.53)
;; WHEN: Mon Aug 05 19:48:49 CST 2019
;; MSG SIZE rcvd: 58
Can you help with it? thanks in advance.
Help with what exactly? What is wrong with this DNS reply for you?
Seems totally legit.
what the helps I asked is that this server (127.0.0.53) returns many timeout
during my
modperl querying process.
I think I may ask the sysadmin to add more caching servers and make them have
good network
connection with internet, am I right?
thanks & regards.
Paulina
