dns lookups

Checking /etc/resolv.conf Name Servers

Linux servers can use /etc/resolv.conf to list name servers that the server will use when trying to convert a domain name (like example.com) to an IP address (like 10.1.1.1) that it can use.

/etc/resolv.conf can have one or more name server entries. If one name server is not working, then the server will attempt to use another one.

If one of the name servers in the /etc/resolv.conf is not working then you can see all sorts of 'odd' problems crop up on your server. Basically anything that does a domain name lookup can be affected. e.g. mail receiving could get slowed down (e.g. if your mail server converts the IP address of the server it is connecting to to a domain name via its ptr dns record).

Typically the symptom will be that tasks that require lookups take a 'long time' (30 seconds to a few minutes) to complete. Since the server may be trying non-responsive name servers and waiting for a dns timeout.

To check that your name server entries are working run the following:

ns=$(cat /etc/resolv.conf  | grep -v '^#' | grep nameserver | awk '{print $2}')
for i in $ns; do ptr=$(host $i | sed 's/Name: //' | sed 's/ .*//g' | head -n 1)
  if dig @$i -t ns rimuhosting.com |grep -qai 'zoneedit'; then 
    echo $i $ptr OK; 
  else 
    echo $i $ptr failed; 
fi; 
done

Name Servers Used On RimuHosting Servers

RimuHosting try to use the name servers provided by the data centers at which we have our servers. So the name server IPs you have may vary depending on where your server with us is located.

Dallas: nameserver 72.249.0.34 nameserver 206.123.69.254

Brisbane: nameserver 202.125.32.4 nameserver 202.125.32.5

London 1) nameserver 193.26.222.2 nameserver 83.142.24.2

London 2) nameserver 217.112.88.90 nameserver 217.112.87.147 nameserver 217.112.88.10

NY/other: nameserver 66.199.235.50 nameserver 72.9.108.146

Note that these name servers may only work if your server is at the named data center (the data center name servers may ignore requests coming from IPs other than from within its network).

Note that RimuHosting runs a few name servers (e.g. ns1.rimuhosting.com, ns2, etc). Please do _not_ use these name servers. Our name servers will _only_ resolve a domain if the domain happens to be hosted on our name servers. Our name servers are not general recursor name servers. So do not have and will not return DNS looks for zones they do not host.