nEdge can enforce a specific DNS server to be used by the LAN devices. nEdge ships with some preset of secure DNS servers, which provide an additional security against malware sites.
The Global DNS is the DNS server used in the following cases:
- When the DHCP server is enabled in routing mode, it will configure the non child-safe clients to use these DNS servers
- By the nEdge device for interfaces configured in static address mode
If the Enforce Global DNS option is set, nEdge will enforce the use of the specified Global DNS even if the clients manually change their DNS servers.
Secure DNS servers can be chosen from the provided presets or be specified manually.
The Child Safe DNS is the DNS used for users which are marked with the Child Safe option.
Such DNS can protect the children from inappropriate adult content.
Note: nEdge will always enforce the use of such a DNS for all the child safe users, even if they manually change their DNS servers.
DNS issue: 5 seconds delay¶
Due to a bug into the kernel, there is an issue with the DNS resolver of some versions of glibc, which causes a client program to stuck for about 5 seconds when performing A and AAAA DNS requests using the same socket. This can be verified with the following command:
When the issue occurs, the command above will increase the insert_failed counter. A temporary solution to the issue is to force glibc to use a different socket for the AAAA request. On a linux client, this can be done by adding the following line to /etc/resolv.conf: