On 25.07.19 00:41, Devilindisguise wrote:
We have what is probably an easy one. Some Windows servers use a locally installed Squid proxy instance for all outbound traffic. These servers also make use of some F5 GTM (DNS) servers to provide a resilient inter-DC DNS topology. Essentially what should happen is under steady state conditions any DNS request should be given IP address a.a.a.a, then under failure be given b.b.b.b. The GTM DNS TTL is 30 seconds. What we’re finding is that even after 5 mins of failure any HTTP request from IE (configured with the Squid proxy) still targets a.a.a.a and traffic is dropped. During this period if we remove the Squid proxy from the IE settings, it works as now we target b.b.b.b. So clearly some sort of caching, possibly DNS, is being done on the Squid.
One of main points of DNS design is to be cacheable. That is why DNS is not suited for load balancing and failover switching. however, you should be able to look at content of DNS cache in squid using cachemgr.cgi to see what's wrong there. also, you can sniff the DNS traffic to see if only proper responses are going to squid. -- Matus UHLAR - fantomas, uhlar@xxxxxxxxxxx ; http://www.fantomas.sk/ Warning: I wish NOT to receive e-mail advertising to this address. Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. REALITY.SYS corrupted. Press any key to reboot Universe. _______________________________________________ squid-users mailing list squid-users@xxxxxxxxxxxxxxxxxxxxx http://lists.squid-cache.org/listinfo/squid-users
