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PPTP/DNS Resolution Times out

Posted: Tue Dec 04, 2012 6:27 pm
by pchaxor
I have 4 Mikrotik routers and love them all very much. (we also use them on all of our WIS towers)

Routers in the mix...
1. Corp (5.21) Main Router
2. Hotel (5.21) VPN is secured and used for staff only!
3. Branch Office (5.21) (less than 5 Users)
4. Home (6.04rc5) (used by me to do some admin work from home and test latest OS/FW)

All connect and do VPN via pptp to #1 Corp and it works great. I can ping host names and connect to Exchange, Sharepoint, IM etc...
Behind the #1 corp router I have two MS DNS servers 192.168.1.55 and 192.168.1.54 both are reachable and specified in the DHCP server in all routers.
I have also specified the domain suffix in the DHCP settings so that it also adds the local domain prefix to host names automatically. Works great!

The problem:
On routers 2,3,4 pptp the DNS resolution times out on the clients randomly. I can still ping 192.168.1.55 and all other IP's but can no longer ping the host names on the pptp network. I have to release and renew the DHCP lease or reboot the affected router to get the DNS resolution back. This happens on Win7, iPad, WinXP and Linux so it doesn't matter what OS. Definitely an issue within the RouterOS. Perhaps a bug even?

Update:
I have set all but Router 4 (home) to auto reboot at 5AM daily to try and prevent the issue from disrupting productivity, however this happens at random times and does not affect all routers at the same time so this is really not a good solution. Rebooting router #1 does not fix the problem so it is definitely an issue with the client pptp router. It also happened again this am (12.6.2012) on router 4.

Perhaps I will submit a ticket to Mikrotik support and see if they can help, was really hoping the community could help with this one.

Re: PPTP/DNS Resolution Times out

Posted: Mon Dec 10, 2012 2:39 pm
by pchaxor
I resolved this issue by hosting the DNS on the router and specifying the router IP in DHCP as the (ONLY/SINGLE) DNS Server.

I also had to:
1. IP - DHCP Client - Edit Client (double click) - Uncheck Use Peer DNS
2. IP - DNS - Servers/Add: 192.168.1.55, 192.168.1.54, 8.8.8.8. 8.8.4.4

This is the only way to resolve the DNS issue since many DHCP clients use RRdns. (Round Robin DNS)
This puts a slight load on the router but not anything that is going to be noticeable with less than 100 clients.

Thanks for the help on this Maris!
Love these Mikrotik Routers!