Intermittent Connection Problem to WWW
Official PPRuNe Chaplain
Joined: Apr 2001
Posts: 3,498
Likes: 0
From: Witnesham, Suffolk
I still reckon there's something wrong with their DNS setup if you can click to some www addresses and not others.
The only places your machine can find the IP address for a www you type into it, is either from a cache it's storing, or from the DNS server your ISP told it about.
I've had the problem a few times when my ISP has changed DNS servers, or when a site I use has changed its IP address and the change hasn't percolated through the system yet.
(That's where the TTL (Time To Live) for the IP address matters - if it's set to a long time, the DNS server probably won't refresh till the TTL is up. If it's too short, that can cause other problems.)
If there are a few addresses that you use a lot, then post 'em here and I'll look up an IP address that you can "fix" into your hosts file - that'll make it use those IPs rather than the DNS results. It's a kludge, but it works (I've done it a few times in the past).
The only places your machine can find the IP address for a www you type into it, is either from a cache it's storing, or from the DNS server your ISP told it about.
I've had the problem a few times when my ISP has changed DNS servers, or when a site I use has changed its IP address and the change hasn't percolated through the system yet.
(That's where the TTL (Time To Live) for the IP address matters - if it's set to a long time, the DNS server probably won't refresh till the TTL is up. If it's too short, that can cause other problems.)
If there are a few addresses that you use a lot, then post 'em here and I'll look up an IP address that you can "fix" into your hosts file - that'll make it use those IPs rather than the DNS results. It's a kludge, but it works (I've done it a few times in the past).
Administrator
Joined: Mar 2001
Aviation Qualifications: PPL
Posts: 8,121
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From: Twickenham, home of rugby
(That's where the TTL (Time To Live) for the IP address matters - if it's set to a long time, the DNS server probably won't refresh till the TTL is up. If it's too short, that can cause other problems.)
TTL is simply the number of gateways an IP packet can pass through before it is discarded. Each gateway decrements the TTL number in the IP packet header by one, until it reaches zero - at which point it is discarded. This was introduced into the IP spec. way back (I forget which RFC covers it) to avoid packets entering infinite loops.
SD
Thread Starter
Nemo Me Impune Lacessit
Joined: Jun 2004
Posts: 4,103
Likes: 5
From: Chabanais, France
Eureka!!! - but I don't know why!
Had a long session on the 'phone with the next level of help, plenty tried, nothing resolved, elevated to an even higher level and told I would be contacted in 5 - 6 working days but this morning all is up and running as fast as it should! I guess they found a problem at their end?
Thanks again to everyone who has contributed and in particular to Keef and Saab Dastard.
Thanks again to everyone who has contributed and in particular to Keef and Saab Dastard.
Official PPRuNe Chaplain
Joined: Apr 2001
Posts: 3,498
Likes: 0
From: Witnesham, Suffolk
dns1.dsc.net. [213.161.73.150] [TTL=259200]
dns2.dsc.net. [213.161.73.134] [TTL=259200]
If you look up the DNS server for pprune.org, you will find that information.
It tells your DNS server how long to cache that particular record before it should be checked - and 259200 is a bit long, by the way.
More information about TTL on DNS records can be found here.
Official PPRuNe Chaplain
Joined: Apr 2001
Posts: 3,498
Likes: 0
From: Witnesham, Suffolk
Had a long session on the 'phone with the next level of help, plenty tried, nothing resolved, elevated to an even higher level and told I would be contacted in 5 - 6 working days but this morning all is up and running as fast as it should! I guess they found a problem at their end?
