Primary vs Secondary DNS Servers - Forwarders?

[scubeedu2]

I have both a primary and secondary DNS server setup and working great. The zones in the secondary server sync properly, however I noticed today that when my primary DNS server went down, I could no longer get out to the internet. Internal sites resolved fine and I have both DNS servers defined as those to be used for DNS queries.

Does the secondary DNS server do DNS forwarding like the primary server, or what might be misconfigured?

[Hemsby]

Have you allowed recursion on the secondary? Have you set the same forwarders on secondary as you did on primary?

[scubeedu2]

Yes, same forwarders on Secondary and Primary. For the secondary and primary, recursion is the default - "Allow Recursion Only For Private Networks (default)" :-)

[ShreyasZare]

Thanks for the post. What output you see when you run nslookup example.com. command from any client when your primary is down? Also, what output do you see when you query for the same domain name in the DNS Client tab on the secondary DNS server's admin panel?

[scubeedu2]

I'll do this test tomorrow morning when nobody is working and get back to you. Thanks!

[scubeedu2]

OK, so this morning it seemed to work properly. Not sure why, but it did take a minute or so for things to come back up; probably because windows took time to switch to the secondary DNS. Regardless, here is the result of the commands you asked about after it started resolving:

C:\Users\Home>nslookup google.com

DNS request timed out.
timeout was 2 seconds.
Server: UnKnown
Address: 192.168.0.113 <--- this is my primary DNS

DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
*** Request to UnKnown timed-out

---

{
"Metadata": {
"NameServer": "vm-dns2.home.lan ([::1])",
"Protocol": "Udp",
"DatagramSize": "167 bytes",
"RoundTripTime": "18.97 ms"
},
"EDNS": {
"UdpPayloadSize": 1232,
"ExtendedRCODE": "NoError",
"Version": 0,
"Flags": "None",
"Options": [
{
"Code": "EXTENDED_DNS_ERROR",
"Length": "28 bytes",
"Data": {
"InfoCode": "Synthesized",
"ExtraText": "Result from negative cache"
}
}
]
},
"Identifier": 0,
"IsResponse": true,
"OPCODE": "StandardQuery",
"AuthoritativeAnswer": false,
"Truncation": false,
"RecursionDesired": true,
"RecursionAvailable": true,
"Z": 0,
"AuthenticData": false,
"CheckingDisabled": false,
"RCODE": "NoError",
"QDCOUNT": 1,
"ANCOUNT": 6,
"NSCOUNT": 0,
"ARCOUNT": 1,
"Question": [
{
"Name": "google.com",
"Type": "A",
"Class": "IN"
}
],
"Answer": [
{
"Name": "google.com",
"Type": "A",
"Class": "IN",
"TTL": "111 (1m51s)",
"RDLENGTH": "4 bytes",
"RDATA": {
"IPAddress": "142.250.137.138"
},
"DnssecStatus": "Disabled"
},
{
"Name": "google.com",
"Type": "A",
"Class": "IN",
"TTL": "111 (1m51s)",
"RDLENGTH": "4 bytes",
"RDATA": {
"IPAddress": "142.250.137.102"
},
"DnssecStatus": "Disabled"
},
{
"Name": "google.com",
"Type": "A",
"Class": "IN",
"TTL": "111 (1m51s)",
"RDLENGTH": "4 bytes",
"RDATA": {
"IPAddress": "142.250.137.101"
},
"DnssecStatus": "Disabled"
},
{
"Name": "google.com",
"Type": "A",
"Class": "IN",
"TTL": "111 (1m51s)",
"RDLENGTH": "4 bytes",
"RDATA": {
"IPAddress": "142.250.137.139"
},
"DnssecStatus": "Disabled"
},
{
"Name": "google.com",
"Type": "A",
"Class": "IN",
"TTL": "111 (1m51s)",
"RDLENGTH": "4 bytes",
"RDATA": {
"IPAddress": "142.250.137.113"
},
"DnssecStatus": "Disabled"
},
{
"Name": "google.com",
"Type": "A",
"Class": "IN",
"TTL": "111 (1m51s)",
"RDLENGTH": "4 bytes",
"RDATA": {
"IPAddress": "142.250.137.100"
},
"DnssecStatus": "Disabled"
}
],
"Authority": [],
"Additional": [
{
"Name": "",
"Type": "OPT",
"Class": "1232",
"TTL": "0 (0s)",
"RDLENGTH": "32 bytes",
"RDATA": {
"Options": [
{
"Code": "EXTENDED_DNS_ERROR",
"Length": "28 bytes",
"Data": {
"InfoCode": "Synthesized",
"ExtraText": "Result from negative cache"
}
}
]
},
"DnssecStatus": "Disabled"
}
]
}