Thread: Peculiar latency problem when changing dns servers

For the last 2 weeks I have had a very strange problem with latencies when I use google/reliance dns.

Usually; say I start off with a 290ms latency to a certain server.
After about an hour - maybe less or more; Slowly this latency will increase by about 100ms to say 370-390ms.

When this happens there is a noticeable lag.
Eventually there is even some packet loss.

Then I repeatedly switch between different dns servers; or simply reconnect to the same connection and the problem goes back to square one.

Code:

Reply from 66.199.244.82: bytes=32 time=368ms TTL=52
Reply from 66.199.244.82: bytes=32 time=365ms TTL=52
Reply from 66.199.244.82: bytes=32 time=372ms TTL=52
Reply from 66.199.244.82: bytes=32 time=367ms TTL=52
Reply from 66.199.244.82: bytes=32 time=374ms TTL=52
Reply from 66.199.244.82: bytes=32 time=369ms TTL=52
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 66.199.244.82: bytes=32 time=370ms TTL=52
Reply from 66.199.244.82: bytes=32 time=370ms TTL=52
Reply from 66.199.244.82: bytes=32 time=370ms TTL=52
Reply from 66.199.244.82: bytes=32 time=367ms TTL=52
Reply from 66.199.244.82: bytes=32 time=368ms TTL=52
Request timed out.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 192.168.1.1: Destination net unreachable.
Reply from 66.199.244.82: bytes=32 time=313ms TTL=50
Reply from 66.199.244.82: bytes=32 time=286ms TTL=50
Reply from 66.199.244.82: bytes=32 time=287ms TTL=50
Reply from 66.199.244.82: bytes=32 time=292ms TTL=50
Reply from 66.199.244.82: bytes=32 time=285ms TTL=50
Reply from 66.199.244.82: bytes=32 time=294ms TTL=50
Reply from 66.199.244.82: bytes=32 time=285ms TTL=50
Reply from 66.199.244.82: bytes=32 time=288ms TTL=50
Reply from 66.199.244.82: bytes=32 time=286ms TTL=50
Reply from 66.199.244.82: bytes=32 time=292ms TTL=50
Reply from 66.199.244.82: bytes=32 time=286ms TTL=50
Reply from 66.199.244.82: bytes=32 time=286ms TTL=50
Reply from 66.199.244.82: bytes=32 time=287ms TTL=50
Reply from 66.199.244.82: bytes=32 time=288ms TTL=50

In the above I try to reconnect twice and then the latency goes back to normal.

This seems to happen throughout the day and to almost any server -
After any variable length of time - anywhere between 15 minutes an 1 hour; latency will slowly creep up to 100-150ms above normal.

Then I try connecting and reconnecting my internet with dialers using different DNS addresses.

Eventually after 4-5 attempts 1 connection will be established with normal latency.

Again after some time the problem repeats itself.

All of this doesn't seem to have much of a correlation on whether or not I'm downloading or torrenting anything.

I have used namebench to pick a good dns server and each time it changes. Regardless I have set up dialers for each of these servers; but the problem crops up in all of them.

1 more thing whenever the latency goes up like this my internet browsing speed goes down significantly with webpages often getting stuck loading.

The problem cropping up after a certain time period often points out to be routing issue. Perhaps BSNL redirects the traffic to the desired server via a congested route.

This is an assumption - may / may not be the effective explanation to what you are facing..

Probably yeah, it's just that it happens ever 20 minutes or so to *all* servers in the EU and US.

Sometimes reconnecting to bsnl repeatedly fixes the problem; but often it doesn't.

Also the problem wasn't happening last month.

traceroute to Product reviews and prices, software downloads, and tech news - CNET

Code:

Tracing route to phx1-rb-gtm1-tron-xw-lb.cnet.com [64.30.224.103]
over a maximum of 30 hops:
  1    12 ms    11 ms    11 ms  59.93.192.1
  2    53 ms    51 ms    53 ms  218.248.255.42
  3    47 ms    47 ms    47 ms  59.163.201.153.static.chennai.vsnl.net.in [59.163.201.153]
  4    70 ms    69 ms    71 ms  172.31.16.173
  5    71 ms    71 ms    75 ms  if-0-100.tcore2.MLV-Mumbai.as6453.net [180.87.39.25]
  6   334 ms   333 ms   333 ms  if-6-2.tcore1.L78-London.as6453.net [80.231.130.5]
  7   346 ms   341 ms   343 ms  Vlan704.icore1.LDN-London.as6453.net [80.231.130.10]
  8   380 ms   379 ms   379 ms  Vlan533.icore1.LDN-London.as6453.net [195.219.83.102]
  9   380 ms   379 ms   379 ms  ae-52-52.csw2.London1.Level3.net [4.69.139.120]
 10   385 ms   379 ms   379 ms  ae-56-221.ebr2.London1.Level3.net [4.69.153.129]
 11   379 ms   379 ms   379 ms  ae-42-42.ebr1.NewYork1.Level3.net [4.69.137.70]
 12   382 ms   385 ms   383 ms  ae-10-10.ebr2.Washington12.Level3.net [4.69.148.50]
 13   382 ms   385 ms   383 ms  ae-1-100.ebr1.Washington12.Level3.net [4.69.143.213]
 14   394 ms   397 ms   397 ms  ae-6-6.ebr1.Atlanta2.Level3.net [4.69.148.105]
 15   396 ms   395 ms   397 ms  ae-63-63.ebr3.Atlanta2.Level3.net [4.69.148.241]
 16   418 ms   417 ms   417 ms  ae-7-7.ebr3.Dallas1.Level3.net [4.69.134.21]
 17   422 ms   421 ms   421 ms  ae-63-63.csw1.Dallas1.Level3.net [4.69.151.133]
 18   422 ms   421 ms   421 ms  ae-61-61.ebr1.Dallas1.Level3.net [4.69.151.126]
 19   450 ms   449 ms   449 ms  ae-1-8.bar1.Phoenix1.Level3.net [4.69.133.29]
 20   449 ms   449 ms   449 ms  ae-0-11.bar2.Phoenix1.Level3.net [4.69.148.114]
 21   460 ms   461 ms   461 ms  ae-5-5.car2.Phoenix1.Level3.net [4.69.148.121]
 22   460 ms   461 ms   461 ms  CBS-CORPORA.car2.Phoenix1.Level3.net [4.53.106.146]
 23   452 ms   451 ms   451 ms  64.30.227.118
 24   448 ms   451 ms   449 ms  phx1-rb-gtm1-tron-xw-lb.cnet.com [64.30.224.103]

Trace complete.

server in new jersey, usa

Here is the traceroute report for the same domain from airtel BB



Clearly the hop count while using BSNL and Airtel becomes different - perhaps this is the cause of the your latency problem..