Question

it might be a dumb question but I'm stuck. I have to subnets on my router 10.0.0.x/24 and 192.168.88.x/24, while ping is working on VM's with 10.0.0.x/24 subnet and they see each other - telnet is adamant in saying that there is no route:

[root@centos7 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 08:00:27:aa:66:2e brd ff:ff:ff:ff:ff:ff
    inet 10.0.0.20/24 brd 10.0.0.255 scope global enp0s3
       valid_lft forever preferred_lft forever
    inet6 fe80::a00:27ff:feaa:662e/64 scope link
       valid_lft forever preferred_lft forever

[root@centos7 ~]# ip route
default via 10.0.0.1 dev enp0s3
10.0.0.0/24 dev enp0s3 proto kernel scope link src 10.0.0.20
169.254.0.0/16 dev enp0s3 scope link metric 1002

[root@centos7 ~]# ping 10.0.0.10
PING 10.0.0.10 (10.0.0.10) 56(84) bytes of data.
64 bytes from 10.0.0.10: icmp_seq=1 ttl=64 time=0.627 ms
64 bytes from 10.0.0.10: icmp_seq=2 ttl=64 time=0.667 ms

[root@centos7 ~]# telnet 10.0.0.10 53
Trying 10.0.0.10...
telnet: connect to address 10.0.0.10: No route to host

Answer 1

[Edited for clarity, and addition of information]

I believe that DNS uses UDP by preference (or at least it used to... I'm an old-timer). "No route to host" probably indicates that somewhere along the path (which essentially means "on the nameserver" in this case) the traffic to tcp port 53 is being denied by a firewall, as you obviously have a route to get there. If you have access, log into 10.0.0.10 as root and check "iptables --list" to see if there's a rule in place to block traffic to that port.