fosiul01
asked on
Related question : Dns server querly is slow
Ref : https://www.experts-exchange.com/questions/25849255/Dns-query-is-slow.html
Hi
Please have a look at network diagram
2 isp is going into a load balancer . From load balancer is going to a firewall.
all client pc is getting IP via dhcp server ( windows SBS 2003 server) and dns query is resolving by SBS 2003 Server.
so client IP address :
IP address example 1 :
192.168.1.10
Gateway : 192.168.1.1.
subnet : 255.255.255.0
DHCP Server : 192.168.1.6
Dns : 192.168.1.6 ( this the ip of SBS Server)
Win :192.168.1.6
Now problem is :
if i turned on both isp line , i can browse properly
but if i turned off isp1 , i can browse via isp2, but its tooo slow
but if i turned of isp2, but keep on isp1, its fine, i can browse fast.
so some how, there is a problem between my SBS Server and isp2, but dont understand what ...
extra note :
now if i hard coded isp2 dns servcer like this
Ip address example 2 :
192.168.1.10
Gateway : 192.168.1.1
subnet : 255.255.255.0
Dns : 10.0.0.12 ( dns server address of isp2)
i can browse fast there is not any problem
but with ip address example 1, browsing via isp2 line is tooo slow
so i am guessing problem could of on dns server on SBS SErver
and i am not a windows guy, so can any one help me to pin point the issue ???
i did not configure this SBS server, so the previous IT guy he used some sort of forwarder aswell...
thanks
also : after putting new ip forwarder, do you have to restart dns server ??
Network-Problem.png
dnsquery.GIF
dnsinterface.GIF
Hi
Please have a look at network diagram
2 isp is going into a load balancer . From load balancer is going to a firewall.
all client pc is getting IP via dhcp server ( windows SBS 2003 server) and dns query is resolving by SBS 2003 Server.
so client IP address :
IP address example 1 :
192.168.1.10
Gateway : 192.168.1.1.
subnet : 255.255.255.0
DHCP Server : 192.168.1.6
Dns : 192.168.1.6 ( this the ip of SBS Server)
Win :192.168.1.6
Now problem is :
if i turned on both isp line , i can browse properly
but if i turned off isp1 , i can browse via isp2, but its tooo slow
but if i turned of isp2, but keep on isp1, its fine, i can browse fast.
so some how, there is a problem between my SBS Server and isp2, but dont understand what ...
extra note :
now if i hard coded isp2 dns servcer like this
Ip address example 2 :
192.168.1.10
Gateway : 192.168.1.1
subnet : 255.255.255.0
Dns : 10.0.0.12 ( dns server address of isp2)
i can browse fast there is not any problem
but with ip address example 1, browsing via isp2 line is tooo slow
so i am guessing problem could of on dns server on SBS SErver
and i am not a windows guy, so can any one help me to pin point the issue ???
i did not configure this SBS server, so the previous IT guy he used some sort of forwarder aswell...
thanks
also : after putting new ip forwarder, do you have to restart dns server ??
Network-Problem.png
dnsquery.GIF
dnsinterface.GIF
If each line is with a different isp then set forwarders for both isp's in the forwarders tab, or use forwarders to DNS servers not bound to either ISP, and you do not need to restart the dns service.
Here are some open dns server you could use as forwarders
208.67.222.222 (resolver1.opendns.com)
208.67.220.220 (resolver2.opendns.com)
208.67.222.222 (resolver1.opendns.com)
208.67.220.220 (resolver2.opendns.com)
ASKER
Hi
If each line is with a different isp then set forwarders for both isp's in the forwarders tab ::
i guess this is how current set up is. . please have a look at both pictures.
if you look at 2nd pic (dnsquery.GIF )
xx.xx.xx.xx and yy.yy.yy.yy is the First isp
zz.zz.zz.zz ( 10.0.0.0.12) is the 2nd isp
what you meant by this
use forwarders to DNS servers not bound to either ISP,
please have a look top 2 picture from Dns server configuration. and i said, by default All client pc is getting Dns Server IP of 192.168.1.6, which is the SBS server itself ( ref to my comment at question, "ip address example 1" )
If each line is with a different isp then set forwarders for both isp's in the forwarders tab ::
i guess this is how current set up is. . please have a look at both pictures.
if you look at 2nd pic (dnsquery.GIF )
xx.xx.xx.xx and yy.yy.yy.yy is the First isp
zz.zz.zz.zz ( 10.0.0.0.12) is the 2nd isp
what you meant by this
use forwarders to DNS servers not bound to either ISP,
please have a look top 2 picture from Dns server configuration. and i said, by default All client pc is getting Dns Server IP of 192.168.1.6, which is the SBS server itself ( ref to my comment at question, "ip address example 1" )
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ASKER
Your main forwarders are to isp1, you kill that link and you are now connected to isp2, however isp2 won't let you connect to isp1 dns servers because they are not public, so it ends up using roots hhints which takes longer to resolve.
this is it, i was thinking this way aswell but in different way
but it could be like this
if you look at 2nd pic , dnsquery.gif...
first 2 ip (xx.xx.xx.xx , yy.yy.yy.yy ) is for isp 1 and zz.zz.zz.zz is for isp 2 and there is 5 sec time [ number of sec before forward query times out ]
so when i kill isp1 link,
all dns query try to go via isp2 and try to do a dns query on isp1 dns server, but isp1 dns server reject those as they are not authoritive .
so 2 ip 5+5 = 10 sec delay
then it try to 3rd ip zz.zz.zz.zz .. its get successful and i am getting webpage after 10 sec which is a big delay
if that true
then my option is not use forwarder
but will it slow down dns query ???
[ i dont want to use open dns servers]
this is it, i was thinking this way aswell but in different way
but it could be like this
if you look at 2nd pic , dnsquery.gif...
first 2 ip (xx.xx.xx.xx , yy.yy.yy.yy ) is for isp 1 and zz.zz.zz.zz is for isp 2 and there is 5 sec time [ number of sec before forward query times out ]
so when i kill isp1 link,
all dns query try to go via isp2 and try to do a dns query on isp1 dns server, but isp1 dns server reject those as they are not authoritive .
so 2 ip 5+5 = 10 sec delay
then it try to 3rd ip zz.zz.zz.zz .. its get successful and i am getting webpage after 10 sec which is a big delay
if that true
then my option is not use forwarder
but will it slow down dns query ???
[ i dont want to use open dns servers]
ASKER
your damm true.
i just put isp2 ip in top then isp1 ip, now when i switch to isp2 line
i can browse properly!!
i just put isp2 ip in top then isp1 ip, now when i switch to isp2 line
i can browse properly!!
You can remove all forwarders if you like and just use root hints, but they are not very reliable (hence your current slow resolution problem)
There is no harm in using public dns servers, maybe just try them for a time and see how it works out?
There is no harm in using public dns servers, maybe just try them for a time and see how it works out?
ASKER
what i am planning to do is :
we have couple of public vps server. I will make 2 of them as dns server for our organization and will allow those dns server to resolve dns queries only from this 2 ip
hope that should solved the issue
is not it ?? its same as using google dns server but its my own .
we have couple of public vps server. I will make 2 of them as dns server for our organization and will allow those dns server to resolve dns queries only from this 2 ip
hope that should solved the issue
is not it ?? its same as using google dns server but its my own .
Yup same thing and a good idea if you have the servers you can use.
ASKER
thanks mate
i knew this could be reason but since dont have too much knowledge of windows , i was not 100% sure
thanks anyway
i will take it from here
i knew this could be reason but since dont have too much knowledge of windows , i was not 100% sure
thanks anyway
i will take it from here
ASKER
thanks
Delete the forwarders should be considered.