Routing And Failover Paths
183 incident problems about Routing And Failover Paths. Start with the reviewed ones.
Read first
When DNS changed but some clients still hit the old backendAn InfraTree guide that lays out the first signals to check, the CLI verification order, common misdiagnoses, and a safe recovery path when the DNS record is updated but resolver cache, HTTP/2 keepalive, or client pools hold on to the old target.Network3 min readWhen firewalld looks open but connections keep getting blockedAn InfraTree guide that lays out the first signals to check, the CLI verification order, common misdiagnoses, and a safe recovery path when a port rule appears to exist but the connection fails because of zone, runtime/permanent drift, source binding, or an upstream firewall.Network3 min readHow to separate timeout and connection refused by network pathAn InfraTree guide that lays out the first signals to check, the CLI verification order, common misdiagnoses, and a safe recovery path when DNS, route, firewall, proxy, and listener states all look like the same connection failure.Network3 min read
Recommended problems
Reviewed problems first, then problems with detailed scenarios.
NETWORK-064ACL shadow rule blocks load balancer health checks from the SNAT poolUser traffic seems permitted on paper, but backends stay marked unhealthy because the firewall never allowed the translated health-check source range.ReviewedNetworkIntermediate18 minFreeNETWORK-1615A BGP session comes up and traffic still exits wrongTraffic still exits the old path after a BGP preference change.ReviewedNetworkBeginner7 minFree
All problems (183)
NETWORK-064ACL shadow rule blocks load balancer health checks from the SNAT poolUser traffic seems permitted on paper, but backends stay marked unhealthy because the firewall never allowed the translated health-check source range.ReviewedNetworkIntermediate18 minFreeNETWORK-1615A BGP session comes up and traffic still exits wrongTraffic still exits the old path after a BGP preference change.ReviewedNetworkBeginner7 minFreeNETWORK-079OSPF virtual link stays downArea IDs still look familiar, but the virtual link cannot form because the transit area assumptions were broken during a partial topology cleanup.NetworkIntermediate17 minFreeNETWORK-069Internal clients cannot reach the public VIPExternal users connect normally, yet internal users fail on the same FQDN because the firewall does not hairpin the connection back to the inside service path.NetworkIntermediate16 minFreeNETWORK-061DHCP relay helper is missing on the new SVI and only remote VLAN clients lose leasesLocal hosts work normally, but one moved VLAN never gets addresses because the relay path was not recreated on the replacement interface.NetworkBeginner15 minFreeNETWORK-1627A route-map change is correct and one neighbor still learns old communitiesOne neighbor still learns old communities after a route-map change.NetworkBeginner8 minFreeNETWORK-1659A route-map change is correct and one neighbor still learns old communitiesOne neighbor still learns old communities after a route-map change.NetworkBeginner8 minFreeNETWORK-1669A route-map change is correct and one neighbor still learns old communitiesOne neighbor still learns old communities after a route-map change.NetworkBeginner8 minFreeNETWORK-1675A route-map change is correct and one neighbor still learns old communitiesA BGP neighbor still learns old communities after the route-map was updated.NetworkBeginner8 minFreeNETWORK-1686A route-map change is correct and one neighbor still learns old communitiesA neighbor still learns old communities after the route-map was updated.NetworkBeginner8 minFreeNETWORK-1696A route-map change is correct and one neighbor still learns old communitiesA neighbor still learns old communities after a route-map update.NetworkBeginner8 minFreeNETWORK-1716A route-map change is correct and one neighbor still learns old communitiesA neighbor still learns old communities after a route-map update.NetworkBeginner8 minFreeNETWORK-1726A route-map change is correct and one neighbor still learns old communitiesA neighbor still learns old communities after a route-map update.NetworkBeginner8 minFreeNETWORK-1736A route-map change is correct and one neighbor still learns old communitiesA neighbor still learns old communities after the route-map update.NetworkBeginner8 minFreeNETWORK-1746A route-map change is correct and one neighbor still learns old communitiesA neighbor still learns old communities after a route-map update.NetworkBeginner8 minFreeNETWORK-1766A route-map change is correct and one neighbor still learns old communitiesA neighbor still learns old communities after a route-map update.NetworkBeginner8 minFreeNETWORK-1816A route-map is correct and one neighbor still learns stale communitiesA neighbor still learns stale communities after the route-map update.NetworkBeginner8 minFreeNETWORK-1826A route-map is correct and one neighbor still learns stale communitiesA neighbor still learns stale communities after the route-map update.NetworkBeginner8 minFreeNETWORK-1836A route-map is correct and one neighbor still learns stale communitiesA neighbor still learns stale communities after the route-map update.NetworkBeginner8 minFreeNETWORK-1846A route-map is correct and one neighbor still learns stale communitiesA neighbor still learns stale communities after the route-map update.NetworkBeginner8 minFree