This response is a wee bit delayed... but I wanted to doublecheck behaviour first.
I wrote this Knowledgebase article last year in order to try and explain some of the things that can happen when monitoring using hostname: http://support.ipswitch.com/kb/WG-20030613-DM02.htm Now, DDNS is not explicitly mentioned in the article. However, I suspect that the Time to Live (TTL) of the hostnames is affecting what you are seeing. 1) You configure a device in WUG with hostname x, using "Poll using hostname" 2) As soon as the device is polled, WUG performs a gethostbyname query and the IP field is filled. 3) WUG will perform additional gethostbyname queries as the TTL on the previous response expires. I set up 60 second frequency monitor on a webserver with an A record with a configured TTL of 300. Sometimes the DNS response will say the TTL is 300. WUG will then go through 4 poll cycles without performing a DNS query and will poll with a DNS query on the fifth cycle.. the TTL has expired. Sometimes the DNS response will say the TTL is 0 and then WUG will poll with a fresh DNS query on the very next cycle. 4) If the answer returned by the DNS query changes then WUG will switch to using that IP. In my trial, WUG performed 7 DNS queries in 20 minutes, and got 5 different replies... so switched IP 4 times. Now, I happened to be monitoring a webserver that was using DNS as a load balancing mechanism... hence the constantly changing DNS answers. But this should be indestinguishable to what would come back if there was just one physical web server and it was using DDNS. What I am thinking happened in your case was that the TTL on the DNS responses was long enough that nothing was actually changing in the period that you were monitoring for. Watch long enough and DNS queries will be retried... and WUG will switch to the new IP if there is one. Mark Symons Ipswitch, Inc Augusta GA -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Celio Fioravante Benato Sent: Friday, February 27, 2004 12:57 To: [EMAIL PROTECTED] Subject: [WhatsUp Forum] Dynamic DNS monitoring Hi, I have to monitor some remote sites that use dynamic DNS names. The problem is that after I set the host name and host ip address in "properties" to the dynamic DNS name, WUG changes the name in the ip field by the ip it resolved. If the site has his IP address changed WUG fails to ping it until I change the ip address fiel by the DNS name again so WUG is able to resolv the new Ip address and change the ip field. So, I never know if the site is down or it�s IP changed. Does anyone have a idea how to solve this issue? Thanks in advance. C�lio Fioravante Benato - Analista de Redes Redisul Engenharia de Redes www.redisul.com.br - [EMAIL PROTECTED] Curitiba: (55) 41-362-2728 - Bras�lia: (55) 61- 349-8507 Please visit http://www.ipswitch.com/support/mailing-lists.html to be removed from this list. An Archive of this list is available at: http://www.mail-archive.com/whatsup_forum%40list.ipswitch.com/ Please visit http://www.ipswitch.com/support/mailing-lists.html to be removed from this list. An Archive of this list is available at: http://www.mail-archive.com/whatsup_forum%40list.ipswitch.com/
