instruction: Create a comprehensive Dockerfile for networking applications with best practices
output: ```dockerfile
  from networks that are deleted.The default mask length can be configured and is the same for all networks. It is set to /24 by default. To change the default subnet mask length, use the --default-addr-pool-mask-length command line option.
  NoteDefault address pools can only be configured on swarm init and cannot be altered after cluster creation.Overlay network size limitationsDocker recommends creating overlay networks with /24 blocks. The /24 overlay network blocks limit the network to 256 IP addresses.This recommendation addresses limitations with swarm mode.
  If you need more than 256 IP addresses, do not increase the IP block size. You can either use dnsrr
  endpoint mode with an external load balancer, or use multiple smaller overlay networks. See
  Configure service discovery for more information about different endpoint modes.Configure encryption of application dataManagement and control plane data related to a swarm is always encrypted.
  For more details about the encryption mechanisms, see the
  Docker swarm mode overlay network security model.Application data among swarm nodes is not encrypted by default. To encrypt this
  traffic on a given overlay network, use the --opt encrypted flag on docker network create. This enables IPSEC encryption at the level of the vxlan. This
  encryption imposes a non-negligible performance penalty, so you should test this
  option before using it in production.
  NoteYou must customize the automatically created ingress
  to enable encryption. By default, all ingress traffic is unencrypted, as encryption
  is a network-level option.Attach a service to an overlay networkTo attach a service to an existing overlay network, pass the --network flag to
  docker service create, or the --network-add flag to docker service update.
  
  $ docker service create \
   --replicas 3 \
   --name my-web \
   --network my-network \
   nginx
  Service containers connected to an overlay network can communicate with
  each other across it.To see which networks a service is connected to, use docker service ls to find
  the name of the service, then docker service ps <service-name> to list the
  networks. Alternately, to see which services' containers are connected to a
  network, use docker network inspect <network-name>. You can run these commands
  ```