DNS stands for Domain Name System.
It translates domain names into IP addresses.
The internet is based on IP addresses.
However, IP addresses are a long series of arbitrary numbers.
They are difficult to remember and relate to.
Since domain names are alphabetic, they are much easier to remember.
Whenever someone types a domain name in a browser,
a DNS server translates the name into the corresponding IP address.
DNS service is required by following common applications-
- World wide web (www)
- Instant messaging
- Multi-player games
- Peer to peer applications
- Web-services, etc
If a DNS server is down or too slow,
a website or web-service will appear as not available.
This may happen even if the website or web-service itself may be up and running.
Hence, it's important to monitor your DNS server for the following reasons -
- If the DNS server is down, visitors will not be able to visit your website.
- If the DNS server is slow, your website will appear to be slow even if your website is fast.
- A hacker may point your domain name to their server.
DNS monitoring is essential to ensure that an DNS server is available to users 24x7 and
downtime is minimized.
The free service provided by MonTools can monitor your DNS server and
send you free alerts in case of following common issues -
- DNS server down
- DNS server slow
- Domain IP Mismatch
DNS Monitor Settings
The DNS monitor supports following settings -
- Monitoring Interval -
This field lets you select the DNS check interval or DNS monitoring interval.
For example, if you select "1 Hour", then the DNS server is checked once every 1 hour.
Monitoring intervals are supported from 1 minute to 1 day.
- Domain Name -
Domain name or website name to be monitored.
The monitor will check the DNS server if a record for the specified domain/website exists.
- Domain IP -
IP address of the domain or the website.
The monitor will verify that the specified IP address matches the DNS server response.
You can click on the "Auto Detect" button, and our system will automatically
detect the IP address for the given domain (above) and enter it in this field.
- DNS Port -
Applications talk to DNS servers on port 53.
However, for custom applications, it can be some port other than 53.
- DNS Host -
Host name of the DNS server to be monitored.
The monitor will verify that the DNS server is available.
You can click on the "Auto Detect" button, and our system will automatically
detect the DNS servers for the given domain (above) and let you select one.
The monitor can be set to trigger on following conditions-
- DNS Down - This condition is triggered if one or more of the following conditions are true-
- DNS server is down
- Response from DNS server takes longer than specified timeout
- DNS record for the specified domain/website doesn't exist
- IP address returned by the DNS server doesn't match the expected Domain IP
- Connection Error -
This condition is triggered only if DNS server is down.
- Response Time -
This condition can be configured to trigger whenever the response time exceeds a certain time limit.
Additionally, you can set the monitor to trigger on mismatch/match on following DNS records-
- A - address record
Returns a 32-bit IPv4 address, most commonly used to map hostnames to an IP address of the host, but also used for DNSBLs, storing subnet masks in RFC 1101, etc.
- AAAA - IPv6 address record
Returns a 128-bit IPv6 address, most commonly used to map hostnames to an IP address of the host.
- AFSDB - AFS database record
Location of database servers of an AFS cell. This record is commonly used by AFS clients to contact AFS cells outside their local domain. A subtype of this record is used by the obsolete DCE/DFS file system.
- ATMA - ATMA resource record
Used to map DNS domain names to Asynchronous Transfer Mode addresses
- AXFR - AXFR record
DNS zone transfer
- CNAME - Canonical name record
Alias of one name to another: the DNS lookup will continue by retrying the lookup with the new name.
- EID - EID record
- GID - GID record
- GPOS - GPOS record
- HINFO - HINFO record
- ISDN - ISDN record
- IXFR - IXFR record
- KEY - key record
Used only for SIG(0) (RFC 2931) and TKEY (RFC 2930). RFC 3445 eliminated their use for application keys and limited their use to DNSSEC. RFC 3755 designates DNSKEY as the replacement within DNSSEC.
- LOC - Location record
Specifies a geographical location associated with a domain name
- MAILA - MAILA record
Mail agent RRs (Obsolete - see MX)
- MAILB - MAILB record
Mailbox-related RRs (MB, MG or MR)
- MB - MB record
Mailbox domain name (EXPERIMENTAL)
- MD - MD record
Mail destination (Obsolete - use MX)
- MF - MF record
Mail forwarder (Obsolete - use MX)
- MG - MG record
Mail group member (EXPERIMENTAL)
- MINFO - MINFO record
Mailbox or mail list information
- MR - MR record
Mail rename domain name (EXPERIMENTAL)
- MX - mail exchange record
Maps a domain name to a list of message transfer agents for that domain
- NAPTR - Naming Authority Pointer
Allows regular expression based rewriting of domain names which can then be used as URIs, further domain names to lookups, etc.
- NIMLOC - NIMLOC record
- NS - name server record
Delegates a DNS zone to use the given authoritative name servers
- NSAP_PTR - NSAP_PTR record
For domain name pointer, NSAP style
- NSAP - NSAP record
For NSAP address, NSAP style A record
- NULL - NULL record
- NXT - NXT record
Next Domain - OBSOLETE
- PTR - pointer record
Pointer to a canonical name. Unlike a CNAME, DNS processing does NOT proceed, just the name is returned. The most common use is for implementing reverse DNS lookups, but other uses include such things as DNS-SD.
- PX - PX record
X.400 mail mapping information
- RP - Responsible person
Information about the responsible person(s) for the domain. Usually a email address with the @ replaced by a .
- RT - RT record
For Route Through
- SIG - Signature
Signature record used in SIG(0) (RFC 2931) and TKEY (RFC 2930). RFC 3755 designated RRSIG as the replacement for SIG for use within DNSSEC.
- SOA - start of authority record
Specifies authoritative information about a DNS zone, including the primary name server, the email of the domain administrator, the domain serial number, and several timers relating to refreshing the zone.
- SPF - Sender Policy Framework
Specified as part of the SPF protocol in preference to the earlier provisional practice of storing SPF data in TXT records. Uses the same format as the earlier TXT record.
- SRV - Service locator
Generalized service location record, used for newer protocols instead of creating protocol-specific records such as MX.
- TSIG - Transaction Signature
Can be used to authenticate dynamic updates as coming from an approved client, or to authenticate responses as coming from an approved recursive name server similar to DNSSEC.
- TXT - Text record
Originally for arbitrary human-readable text in a DNS record. Since the early 1990s, however, this record more often carries machine-readable data, such as specified by RFC 1464, opportunistic encryption, Sender Policy Framework (although this provisional use of TXT records is deprecated in favor of SPF records), DomainKeys, DNS-SD, etc.
- UID - UID record
- UINFO - UINFO record
- UNSPEC - UNSPEC record
- WKS - WKS record
A well known service description
- X25 - X25 record
For X.25 PSDN address
Whenever the monitor detects the DNS server down or any other issues,
or any other configured conditions are triggered,
it can send you and/or your colleagues a free alert with one or more of the following methods-
- Email alert
- SMS alert
- Twitter alert (private message)
- Callback URL
DNS Logs, Stats & Graphs
Logs, stats and graphs are available for uptime, monitor status and DNS response time.
To create a free DNS monitor, login or create account - free!