Problem with ping host_name in Tru64 V5.1

[Geert Van Pamel]

I cannot ping host names with underscores in Tru64 V5.1. In Tru64 V4.0F and for HP/UX this works OK.

nslookup does not have a problem with underscores. I thought that ping would call first nslookup to translate the host name to an IP address? So I do not understand what is the origin of this ping problem?

/sbin/ping xxx_p.xx
ping: unknown host xxx_p.xx

nslookup xxx_p.xx

Name: xxx_p.xx
Address: 192.168.66.65

This is a real problem for our Oracle 10g database servers, since database connectivity seems to use ping to check if database servers are reachable...

The only workaround I currently see is to add all machines with underscores in every /etc/hosts.

I somewhere read that some DNS servers do not support underscores in host names? Could this be the reason? But why only Tru64 V5 has a problem then?

[Hein van den Heuvel · Accepted solution]

Strictly speakind the underscore is NOT valid.

Add this to /etc/resolv.conf to allow it:
options allow_special { \_ }

related things to check:

- named.conf set "check-names" to ignore".

- resolution order in svc.conf


Underscores were tolerated in OSf V4.0b. Dissalowed in 4.0d, re-allowed through an IMPT patch in 4.0d which carried forward to 4.0f.
V5.1A and later got the tightened rules again.

See RFC 1123, which references RFC 952 and the DNS specification in RFCs 1034 and 1035. The resultant recommeded character set is as stated in RFC 952 (letters, digits, dash, beginning with a letter, ending with a letter or digit) with the relaxation that a name can now also begin with a digit.

RFC 2181 (updated by RFC 2535) also discuss this.

hth,
Hein van den Heuvel
HvdH Performance Consulting

[Ivan Ferreira]

What is the configuration of:

/etc/svc.conf
/etc/nsswitch.conf

Ensure that you have DNS resolution enabled for hosts in both places.

[Geert Van Pamel]

Hein,

Problem solved. I added the option to /etc/resolv.conf

options allow_special { \_ }

Thanks a lot. This way I do not have to add all my Oracle database servers to /etc/hosts!!