DNS causing network issues

domenicodesigns · 02-21-2010, 05:58 PM

Hi guys. I am currently working with a wired network running around six 20" iMac's (10.5) and a 10.5 server, which all run fine together. However the other day we added two 21.5" iMac's (10.6) and they are both connecting to the server extremely slowly (sometimes taking up to 3 minutes to connect).

In an attempt to fix this I did a whole lot of research and trial and error, only to conclude that it is probably a DNS problem. The internet speed on the two 10.6 iMac's is fine, but when I remove the DNS from the network preferences the server connection returns to normal speed. Clearly this isn't a fix though, since no DNS means no internet.

I am not hugely educated on technical networking, so any help would be greatly appreciated.

Also as a side note, is there any compatibility issues between 10.6 machines and 10.5 servers? I ask this because both the 10.6 are migrated copies from 10.5 machines. The two 10.5 machines were then restored to factory settings but still don't encounter this issue. I could just be getting a bum steer there though.

Mailman42 · 02-21-2010, 07:31 PM

on the "good" macs, open a terminal, and type

sudo cat /etc/resolv.conf

note what is in there.

On the 2 "bad" macs, do the same

See if they are the same or if they show something different.

Also, make sure that they are pointing to the same "gateway" as the other macs.

domenicodesigns · 02-21-2010, 08:12 PM

Thanks for the reply. The gateways on all of them are the same.

I ran the terminal line, and they both gave the same nameserver result, however the two "bad" Mac's also gave me this before it;

#

# Mac OS X Notice

#

# This file is not used by the host name and address resolution

# or the DNS query routing mechanisms used by most processes on

# this Mac OS X system.

#

# This file is automatically generated.

#

I am not sure what that means. Could it be the source of the problem?

Mailman42 · 02-21-2010, 08:18 PM

I'm running 10.6.2, so your mileage may vary

Run

System Preferences -> Network -> Advanced -> DNS

on the good machines, and make the 2 bad machines duplicate their entries

domenicodesigns · 02-21-2010, 08:39 PM

The DNS settings for all the machines are exactly the same and all the entries match. I am at quite a loss here...

cwtnospam · 02-21-2010, 09:16 PM

Could the new machines be trying to connect to a wireless network too? Try turning off Airport.

domenicodesigns · 02-21-2010, 09:16 PM

Airport on both machines is off.

cwtnospam · 02-21-2010, 09:18 PM

Any proxies or custom ethernet settings?

domenicodesigns · 02-21-2010, 09:29 PM

No custom ethernet settings, and only a couple of bypass domains in the proxies. The setting for those are the same on all machines. I did attempt to remove the domains just out of desperation on the bad machines, but it was still having the same issues.

cwtnospam · 02-21-2010, 09:35 PM

Have you tried switching ethernet cables and ports with a working machine?

domenicodesigns · 02-21-2010, 09:40 PM

Well because the new machines became the boss' machines and their older ones became staff machines, the new machines are just migrated from the old ones. And because of this they are in the same physical position as the old machines, using the same cables and ports. I was also using the same cable/port to set up the old machine after it had been restored (after the migration) and there was no network issues with it. I can safely rule out cables and ports.

gsahli · 02-21-2010, 09:41 PM

Is IPv6 Off on the new ones?

domenicodesigns · 02-21-2010, 09:44 PM

No, IPv6 is set to 'Automatically', purely in an attempt to completely mimic the other machines. But switching it off doesn't help at all.

cwtnospam · 02-21-2010, 09:56 PM

Is it possible these two Macs are trying to connect to a server that doesn't exist on your network? Maybe one that does exist on a test network?

domenicodesigns · 02-21-2010, 10:06 PM

The odds are slim to none. We don't have a test network and I am the only person who has touched them since they left their box. Also the issue is connecting to a server I specify. All the other machines and the server show up in finder down the left, but when I click them it takes its sweet time to connect to them.

P.S. Thanks for the help so far guys

cwtnospam · 02-21-2010, 10:15 PM

Have you tried rebooting the router?

domenicodesigns · 02-21-2010, 10:17 PM

Sure have. Again, no difference there.

agentx · 02-22-2010, 10:57 AM

Ok a few questions :

Do you connect to server with a FQDN such as macserver.company.com or a macserver.local name ?

Is the server Standalone or OD Master ?

Have you tried turning off Secure connections ?
I found at a couple of sites that the 10.6 machines were trying to connect to server using secure connections this took around two mins before it timed out then it reverted to trying to connect with standard methods.

Are you connecting from Sidebar or using IP from connect to server (try both !)

domenicodesigns · 02-25-2010, 09:19 PM

No, we aren't using FQDN, the server should be OD Master (not 100%, but pretty confident) and its slow connecting both sidebar and 'connect to server'.

As for secure connection, I am not completely sure how to check for that.

agentx · 02-26-2010, 03:23 AM

I personally never setup server without FQDN as some services just do not work correctly without this. If you use OD Master this should be set.

Anyway just for kicks try and turn AFP connections to "Digest"

Server Admin > Servername > AFP > Settings > Acccess > Switch from Any method to Digest.

02-21-2010, 05:58 PM	#1
domenicodesigns Prospect Join Date: Feb 2010 Posts: 13	DNS causing network issues Hi guys. I am currently working with a wired network running around six 20" iMac's (10.5) and a 10.5 server, which all run fine together. However the other day we added two 21.5" iMac's (10.6) and they are both connecting to the server extremely slowly (sometimes taking up to 3 minutes to connect). In an attempt to fix this I did a whole lot of research and trial and error, only to conclude that it is probably a DNS problem. The internet speed on the two 10.6 iMac's is fine, but when I remove the DNS from the network preferences the server connection returns to normal speed. Clearly this isn't a fix though, since no DNS means no internet. I am not hugely educated on technical networking, so any help would be greatly appreciated. Also as a side note, is there any compatibility issues between 10.6 machines and 10.5 servers? I ask this because both the 10.6 are migrated copies from 10.5 machines. The two 10.5 machines were then restored to factory settings but still don't encounter this issue. I could just be getting a bum steer there though.

02-21-2010, 07:31 PM	#2
Mailman42 Major Leaguer Join Date: Sep 2006 Posts: 479	on the "good" macs, open a terminal, and type sudo cat /etc/resolv.conf note what is in there. On the 2 "bad" macs, do the same See if they are the same or if they show something different. Also, make sure that they are pointing to the same "gateway" as the other macs. Last edited by Mailman42; 02-21-2010 at 07:32 PM. Reason: want to add more content

02-21-2010, 08:12 PM	#3
domenicodesigns Prospect Join Date: Feb 2010 Posts: 13	Thanks for the reply. The gateways on all of them are the same. I ran the terminal line, and they both gave the same nameserver result, however the two "bad" Mac's also gave me this before it; # # Mac OS X Notice # # This file is not used by the host name and address resolution # or the DNS query routing mechanisms used by most processes on # this Mac OS X system. # # This file is automatically generated. # I am not sure what that means. Could it be the source of the problem?

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02-21-2010, 08:18 PM	#4
Mailman42 Major Leaguer Join Date: Sep 2006 Posts: 479	I'm running 10.6.2, so your mileage may vary Run System Preferences -> Network -> Advanced -> DNS on the good machines, and make the 2 bad machines duplicate their entries

02-21-2010, 08:39 PM	#5
domenicodesigns Prospect Join Date: Feb 2010 Posts: 13	The DNS settings for all the machines are exactly the same and all the entries match. I am at quite a loss here...

02-21-2010, 09:16 PM	#6
cwtnospam League Commissioner Join Date: Jan 2005 Posts: 8,475	Could the new machines be trying to connect to a wireless network too? Try turning off Airport.

02-21-2010, 09:18 PM	#8
cwtnospam League Commissioner Join Date: Jan 2005 Posts: 8,475	Any proxies or custom ethernet settings?

02-21-2010, 09:29 PM	#9
domenicodesigns Prospect Join Date: Feb 2010 Posts: 13	No custom ethernet settings, and only a couple of bypass domains in the proxies. The setting for those are the same on all machines. I did attempt to remove the domains just out of desperation on the bad machines, but it was still having the same issues.

02-21-2010, 09:35 PM	#10
cwtnospam League Commissioner Join Date: Jan 2005 Posts: 8,475	Have you tried switching ethernet cables and ports with a working machine?

02-21-2010, 09:40 PM	#11
domenicodesigns Prospect Join Date: Feb 2010 Posts: 13	Well because the new machines became the boss' machines and their older ones became staff machines, the new machines are just migrated from the old ones. And because of this they are in the same physical position as the old machines, using the same cables and ports. I was also using the same cable/port to set up the old machine after it had been restored (after the migration) and there was no network issues with it. I can safely rule out cables and ports.

02-21-2010, 09:41 PM	#12
gsahli MVP Join Date: Apr 2004 Location: Chicago Posts: 1,250	Is IPv6 Off on the new ones?

02-21-2010, 09:44 PM	#13
domenicodesigns Prospect Join Date: Feb 2010 Posts: 13	No, IPv6 is set to 'Automatically', purely in an attempt to completely mimic the other machines. But switching it off doesn't help at all.

02-21-2010, 09:56 PM	#14
cwtnospam League Commissioner Join Date: Jan 2005 Posts: 8,475	Is it possible these two Macs are trying to connect to a server that doesn't exist on your network? Maybe one that does exist on a test network?

02-21-2010, 10:06 PM	#15
domenicodesigns Prospect Join Date: Feb 2010 Posts: 13	The odds are slim to none. We don't have a test network and I am the only person who has touched them since they left their box. Also the issue is connecting to a server I specify. All the other machines and the server show up in finder down the left, but when I click them it takes its sweet time to connect to them. P.S. Thanks for the help so far guys

02-21-2010, 10:15 PM	#16
cwtnospam League Commissioner Join Date: Jan 2005 Posts: 8,475	Have you tried rebooting the router?

02-21-2010, 10:17 PM	#17
domenicodesigns Prospect Join Date: Feb 2010 Posts: 13	Sure have. Again, no difference there.

02-22-2010, 10:57 AM	#18
agentx Hall of Famer Join Date: Feb 2003 Location: Brighton, UK Posts: 3,832	Ok a few questions : Do you connect to server with a FQDN such as macserver.company.com or a macserver.local name ? Is the server Standalone or OD Master ? Have you tried turning off Secure connections ? I found at a couple of sites that the 10.6 machines were trying to connect to server using secure connections this took around two mins before it timed out then it reverted to trying to connect with standard methods. Are you connecting from Sidebar or using IP from connect to server (try both !)

02-25-2010, 09:19 PM	#19
domenicodesigns Prospect Join Date: Feb 2010 Posts: 13	No, we aren't using FQDN, the server should be OD Master (not 100%, but pretty confident) and its slow connecting both sidebar and 'connect to server'. As for secure connection, I am not completely sure how to check for that.

02-26-2010, 03:23 AM	#20
agentx Hall of Famer Join Date: Feb 2003 Location: Brighton, UK Posts: 3,832	I personally never setup server without FQDN as some services just do not work correctly without this. If you use OD Master this should be set. Anyway just for kicks try and turn AFP connections to "Digest" Server Admin > Servername > AFP > Settings > Acccess > Switch from Any method to Digest.