Service Unavailable Error

[Dan Murphy]

Get it often here also. Mostly on mobile device.

 

[orum]

For me, it’s increasing in frequency.

As a non-IT guru, what I don’t understand is how it happens in the MIDDLE of a browsing session. Numerous times I’ve had the error pop up as I’m trying to post a comment, or just navigation through the site. It seems to me that once the DNS server(s) has done it magical connection between me and the disboard host, that should be it. It found its way to the new host.

Does the DNS constantly (or periodically) refresh the connection and routing?

There are a few places that the IP address might be cached. First, the browser may cache it so it doesn't even have to go ask the computer for the IP address again. There is also a local DNS cache on the computer/phone/tablet.

The reason it continues to check after while you are in a browser session is in case the server moves. Normally, lowering the TTL (time to live) prior to a move would cause everyone that keeps it in cache to expire it a little quicker so when you actually do the move, there is less downtime to the end user. What is really odd is all of these systems that seem to be picking up the wrong info from somewhere and keeping it alive and re propagating bad address info.

It's like calling a business to get their address. You may write it in your address book so you don't have to call them again, but every once in a while, maybe you call again to make sure they haven't moved. Unfortunately, in this case, every 50 times (or however often it is happening), it isn't an employee picking up the phone and they are giving you the wrong address.

 

[easyas123]

Can you guys let me know what times this is happening? I think I've been noting it around 1pm/2pm Pacific, but not sure.

I've noticed it mid-morning Eastern.
Seems to last about a hour or so, and I've noticed it several times over the past few days.

 

[DLgal]

I have a hard time believing this has nothing to do with the server...

This is not an issue on the user end.

 

[DonMacGregor]

There are a few places that the IP address might be cached. First, the browser may cache it so it doesn't even have to go ask the computer for the IP address again. There is also a local DNS cache on the computer/phone/tablet.

The reason it continues to check after while you are in a browser session is in case the server moves. Normally, lowering the TTL (time to live) prior to a move would cause everyone that keeps it in cache to expire it a little quicker so when you actually do the move, there is less downtime to the end user. What is really odd is all of these systems that seem to be picking up the wrong info from somewhere and keeping it alive and re propagating bad address info.

It's like calling a business to get their address. You may write it in your address book so you don't have to call them again, but every once in a while, maybe you call again to make sure they haven't moved. Unfortunately, in this case, every 50 times (or however often it is happening), it isn't an employee picking up the phone and they are giving you the wrong address.

Gotcha.

The other thing that strikes me as odd (again, as a casual observer), is that so many disparate DNS providers are returning the same error. In my simple mind, I see it as a pyramid, with all the DNS providers at the bottom, and the disboards host at the top. For so many to be experiencing the same error, it can't be occurring down at the bottom, but closer to the top, as the connections are narrowed and funneled towards the same host server. Now, I do get that the interwebs are more of a multi-dimensional and redundant mesh than a funnel, but at some point all of these connections must be passing through the same set of servers that are returning the same error and logically it would seem to be closer to the board's host than all the remote and disparate DNS providers (globally it would now seem).

Again, just questioning to learn, not criticize.

 

[jpeterson]

I've been getting this a lot on all my computers, but often times it will only affect a single computer at a time, or one browser vs another, or even a regular vs incognito window.

I started thinking that one of the forum servers is likely having some issue and they are using "sticky routing". So when we get routed to that server, we stay on that server for the length of a session. A different device/browser/etc counts as a different session.

To play with that I used the NordVPN extension for my browser of choice (Edge, don't judge me). With the VPN on, forums work fine, turn it off and back to the Service Unavailable Error.

 

[orum]

Gotcha.

The other thing that strikes me as odd (again, as a casual observer), is that so many disparate DNS providers are returning the same error. In my simple mind, I see it as a pyramid, with all the DNS providers at the bottom, and the disboards host at the top. For so many to be experiencing the same error, it can't be occurring down at the bottom, but closer to the top, as the connections are narrowed and funneled towards the same host server. Now, I do get that the interwebs are more of a multi-dimensional and redundant mesh than a funnel, but at some point all of these connections must be passing through the same set of servers that are returning the same error and logically it would seem to be closer to the board's host than all the remote and disparate DNS providers (globally it would now seem).

Again, just questioning to learn, not criticize.

I think you are exactly correct. There is some "yellow pages" or "directory assistance" node between you and the disboards DNS server that is holding on to the wrong info, but there isn't an easy way to figure out what server it is. Normally, this just resolves itself relatively quickly (which is not happening in this case).

To prove the server owners did everything right, here is the info they control:
Whois disboards - this entry tells everyone what DNS servers to use. https://www.whois.com/whois/disboards.com
This says these 2 name servers are "authoratative" to tell everyone where disboards is located. ns87.worldnic.com and ns88.worldnic.com

If you run nslookup (on your computer) and specify to ask their servers

nslookup
Default Server: REDACTED

> server ns87.worldnic.com
Default Server: ns87.worldnic.com
Address: 162.159.26.131

> www.disboards.com
Server: ns87.worldnic.com
Address: 162.159.26.131

Name: www.disboards.com
Address: 108.61.75.210

and

nslookup
Default Server: REDACTED

> server ns88.worldnic.com
Default Server: ns88.worldnic.com
Address: 162.159.27.117

> www.disboards.com
Server: ns88.worldnic.com
Address: 162.159.27.117

Name: www.disboards.com
Address: 108.61.75.210

This tells you that the web admins have put in the right info and everyone else should be getting the right numbers after any TTL (time to live) expires.

This isn't going to be an easy problem to fix.

 

[orum]

I've been getting this a lot on all my computers, but often times it will only affect a single computer at a time, or one browser vs another, or even a regular vs incognito window.

I started thinking that one of the forum servers is likely having some issue and they are using "sticky routing". So when we get routed to that server, we stay on that server for the length of a session. A different device/browser/etc counts as a different session.

To play with that I used the NordVPN extension for my browser of choice (Edge, don't judge me). With the VPN on, forums work fine, turn it off and back to the Service Unavailable Error.

This is not a server related issue. The reason this only impacts some machines is the DNS server that is assigned by your internet provider is sometimes a VIP (virtual IP). This is an IP address that goes to a front end and there are multiple servers behind it. This is used to prevent single point of failure issues. I saw on AT&T wireless DNS on my phone that consecutive DNS lookups were giving different info even when querying the same DNS server. One server in the array had bad info so I was only seeing it some of the time.

 

[Mackenzie Click-Mickelson]

This is not a server related issue. The reason this only impacts some machines is the DNS server that is assigned by your internet provider is sometimes a VIP (virtual IP). This is an IP address that goes to a front end and there are multiple servers behind it. This is used to prevent single point of failure issues. I saw on AT&T wireless DNS on my phone that consecutive DNS lookups were giving different info even when querying the same DNS server. One server in the array had bad info so I was only seeing it some of the time.

Are you using your home or other wifi when you're on your phone?

 

[DLgal]

This is not a server related issue. The reason this only impacts some machines is the DNS server that is assigned by your internet provider is sometimes a VIP (virtual IP). This is an IP address that goes to a front end and there are multiple servers behind it. This is used to prevent single point of failure issues. I saw on AT&T wireless DNS on my phone that consecutive DNS lookups were giving different info even when querying the same DNS server. One server in the array had bad info so I was only seeing it some of the time.

So how is it "not a server issue"? You mentioned servers 4 times.

 

[FlightlessDuck]

I get the same error on my phone, on the desktop, and on hubby's laptop , so I know it's not a device problem.

Service Unavailable is HTTP error code 503, which would be returned by the server and wouldn't be related to a user's devices (normally).

 

[FlightlessDuck]

This is not a server related issue. The reason this only impacts some machines is the DNS server that is assigned by your internet provider is sometimes a VIP (virtual IP). This is an IP address that goes to a front end and there are multiple servers behind it. This is used to prevent single point of failure issues. I saw on AT&T wireless DNS on my phone that consecutive DNS lookups were giving different info even when querying the same DNS server. One server in the array had bad info so I was only seeing it some of the time.

Since disboards moved to be hosted by xenforo, it's possible not all DNS servers have been updated yet, so if a DNS table is going to the old IP address, the old server(s) would be what's returning the 503.

 

[lynxstch]

It's happening now on both devices at the same time for me. Couldn't access these boards from my phone or laptop for several hours this morning.

Same thing here

 

[lynxstch]

I've noticed it mid-morning Eastern.
Seems to last about a hour or so, and I've noticed it several times over the past few days.

Eastern time here also--I get it very early morning..then anywhere from 9-noon, and then again yesterday afternoon I got it from 2-5. Last night I tried to get it on my phone around 9 pm and it was down again. It's happening more and more frequently and lasting longer and longer

 

[orum]

So how is it "not a server issue"? You mentioned servers 4 times.

HAHA. Good point. It isn't a disboards server issue. It is an issue with someone else's DNS server somewhere.

 

[orum]

Are you using your home or other wifi when you're on your phone?

depends. In doing some investigation, I was sometimes on my home wifi (comcast with various DNS settings) and others on wireless (AT&T)

 

[orum]

Since disboards moved to be hosted by xenforo, it's possible not all DNS servers have been updated yet, so if a DNS table is going to the old IP address, the old server(s) would be what's returning the 503.

I would normally have expected any downstream DNS server to have updated from the disboards authoritative one by now. I am sure as soon as I post this, the problem will come back, but I am no longer seeing it at home. I am not using Comcast DNS anymore, so others on Comcast may have the issue reoccur.

 

[DLgal]

I would normally have expected any downstream DNS server to have updated from the disboards authoritative one by now. I am sure as soon as I post this, the problem will come back, but I am no longer seeing it at home. I am not using Comcast DNS anymore, so others on Comcast may have the issue reoccur.

I wasn't seeing it earlier and then it suddenly appeared in the middle of a session on my phone. I'm on my tablet now and it's working, but who knows for how long?

 

[Mackenzie Click-Mickelson]

depends. In doing some investigation, I was sometimes on my home wifi (comcast with various DNS settings) and others on wireless (AT&T)

Okay, yeah I'm not using wifi on my phone. The network is T-mobile if using my phone.

 

[Meriweather]

happening more frequently.
Today I couldn't access via Firefox or Edge.....first time Edge has done this