We played around with DNS settings on the SonicWALL, but we knew they shouldn't have been relevant because DNS requests from users are handled by our DNS server. Web browsing was very slow - a real disappointment for Day 1! After a while we figured we had a DNS problem because all our nslookups, pings and tracerts to external sites were failing. It was only when we went live that things unraveled. And don’t forget that you can always find great content still available from all past conferences at the Sharkfest US, Sharkfest Europe, and Sharkfest Asia Retrospective pages tooDuring configuration, testing and initial deployment of the SonicWALL all seemed well.I checked and found one of them still switched on in one of the zones. Content filtering) but our intention was to operate with all those switched off in the first instance in case of performance problems. The router included bundled subscriptions to SonicWALL security services (e.g.There was one we weren't sure about so we disabled it. We went back to checking our settings, including NAT Policies. Opening the Exchange Queue Viewer showed a stack of undelivered messages with - guess what - DNS failures.I searched discussion forums and took some comfort from apparently not being the only one, but the thread I found didn't offer me a solution. Configures the ESBC to support Early Media for inbound calls.Unfortunately it all broke again a few minutes later.To make matters worse, I then realised our Exchange server wasn't sending any email out. LAN Access Control Settings by MAC Address.ARP packetsWe tried a few other changes - like deleting a route policy that forced all HTTPS traffic to use WAN1, regardless of load balancing settings - to no avail.Finally SonicWALL support came up with the goods. It was when we reconnected the secondary connection that it would start to fail. Unfortunately that proved to be a dead end as well.We could tell it was something to do with having two WAN connections because when we ran on only one (which was our faster one), everything was fine. Responses from the community led me to think we'd cracked it and that it was caused by packet splitting when spilling over from one WAN to the other. Eventually we realised that making any setting change on the SonicWALL - enabling or disabling a rule or a policy - would fix it for about 15 minutes.I logged a support case with SonicWALL and also posted on the Spiceworks community. 15 minutes later, it all broke again.
Which Tool Watches For And Ignores Incoming Dhcp Requests From Unknown Addresses? How To Reach UsAfter a while (about 15 minutes in our case), the ISP's ARP cache no longer has any record of how to reach us so doesn't know where to send packets we should receive. The SonicWALL detects these requests as coming from an unknown subnet and promptly drops them as this is regarded as a security risk. Evidently our secondary ISP sends ARP (Address Resolution Protocol) requests to check which of our static IP addresses are in use. Just like the article shows, I could see the relevant IP address and the packets being rejected. Using Packet Capture to see the incoming ARP requests being dropped. (This seems to be what we were effectively doing when we made setting changes, though we didn't realise it.) Using a hidden option to send "gratuitous ARP requests" from the router to restore connectivity. Only more frequent.The SonicWALL article describes three steps to diagnosing and fixing this problem: Hence we lost both connections, and it was just like the bad old days with the Zyxel. Vmware tools download for mac os xIncoming requests from an unrecognized address will be dropped and if they're from your ISP your connection will break. SummaryThis was easy to fix once we found the relevant article but I did begin to wonder if I'd bought a bad router! I'm no expert on networking but I've learnt that ARP requests are important and that normally you'd only see them on your internal LAN. The article does warn that if the ISP ever changes the source IP address for the ARP packets we'll hit the same problem - but this time we'll be prepared and can just change the static route.
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